The wagon train is soon surrounded by a large band of about one hundred yelling Indians. [This Indian attack upon the settlers is visible, unlike the earlier unseen attack that killed Fen's wagon train.] "Saving a bunch of gamblers and women" means pulling all the cowhands off the drive and leaving the cows to drift aimlessly through the sagebrush. Matt and three other men ride into the perimeter of the circled wagons to join the besieged travelers. During the Indian attack, Matt strikes up an acquaintance with one of the members of the train - Tess Millay (Joanne Dru in her second film), a pretty woman who isn't a prostitute, who is courageously shooting at Indian targets circling the wagons. [Her predicament mirrors the one that Fen faced when she lost her life.] While he helps defend the wagon train, she asks: "What are you so mad about? I asked you why you're angry. Is it because - because some of your men might get hurt, killed maybe?" Mid-sentence, she is struck by an arrow in the right shoulder even though Matt had warned her to stay down.

After the Indians are routed by the approach of the other cowpokes, Matt returns to Tess, removes the arrow from her shoulder and sucks the poison out of her wound while she presses him more about his anger: "I asked you before why you were so mad. Is it, is it because your cattle, the cattle Cherry told me about, might run off? Or maybe, maybe you don't like the idea of helping, helping a bunch of...(women)." A feisty, strong woman, she is put off by his attitude toward her (he distances himself because he believes she is one of the loose prostitutes, although in actuality she isn't) and slaps him before fainting into his arms. [When Dunson first met Matt, he also slapped him.] Tess, however, is instantly intrigued by Matt, and asks about him when he doesn't attend the evening's dance celebration, but tends the cattle in the fog. She learns from Groot where he is located and how Matt took the herd away from Dunson.

She seeks him out to talk to him with an affectionate and encouraging manner - revealing her future role as reconciler. She seeks refuge in talk (unlike both Matt and Dunson) - as a therapeutic way to release her heart-felt, emotional feelings:

I'm scared too. That's why I'm talking because it's the best thing to do when you feel that way. Just talk and keep on talking...I talk to myself even if I have to sit in front of a mirror and talk...You can talk to me. I'm right here. It would help. Oh please, you can tell me to mind my own business if you'd like. And if it would help any, you can hit me, like I did you right across the mouth. But it would be good for you to talk, and I'd like to talk to you...Please, I'd really like to talk to ya.

In a very brief love scene, Matt reveals his care for Tom. He portrays Dunson as a single-minded man who seized an opportunity and helped to develop the West - but also refused to surrender to his vulnerability or weaknesses when confronted. Quickly, the heroine Tess falls in love with Matt as it begins to rain - she initiates him sexually:

Tess: Why does he [Dunson] think that way?
Matt: Because he got to a place where, see, he'd taken empty land used for nothin', made it the biggest ranch in the state of Texas. Fought to keep it...one bull and one cow, that's all he started with...After he'd done all that, gotten what he'd been after for so long, it wasn't worth anything...So he started this drive. Everybody said, 'you can't make it. You'll never get there.' He was the only one believed we could. He had to believe it. So he started thinking one way, his way. He told men what to do and made 'em do it. Otherwise, we wouldn't have got as far as we did. He started 'em for Missouri and all he knew was he had to get there. I took his herd away from him.
Tess: You love him, don't you? He must love you. That wouldn't be hard. (She kisses Matt on the lips.) Did you like that?
Matt: I've always been kind of slow in making up my mind.
Tess: Maybe I can help. (They kiss again.)
Matt: I don't need any more help but will you do that again? (They kiss again.)

When a sudden rainstorm causes the river to rise, Matt decides to push on immediately with the herd rather than waiting until morning, leaving his new love Tess behind - something that Dunson did years earlier to Fen. Groot confirms that they can't take Tess with them:

Matt: We can't take her with us, can we?
Groot: Well we could, uh...
Matt: What?
Groot: No, no, I don't suppose we could.

The next page of the diary describes Dunson's pursuit:

And that night they moved. The river was rising, they must get across while there was still time. In the meantime, Dunson had found men and ammunition and taken up the chase. He was determined to overtake Matt...

In his relentless chase after joining up with several gunmen, Dunson rides up to the wagon train. They are told that the cattle trail herd is over a week's journey away and that Matt left the wagon train eight days earlier. Dunson's men are offered a meal and Tess personally offers to feed Dunson: "I'll take care of Mr. Dunson." He is surprised that she knows his name:

Tess: I believe it's your beef we're eating.
Dunson: Who told you that?
Tess: The man you promised to kill.
Dunson: Did he tell you that too?
Tess: You're tired, aren't you? Tired, hungry and just a little bit irritable. You'll feel better after you eat. We'll talk then.

Dunson grabs her wrist, noticing that she is wearing the snake bracelet given to her by Matt. The bracelet (originally linking Fen to Dunson and Matt) now links Matt to Tess. She explains how she was left behind, like Tom had left Fen. Dunson realizes that Matt is re-living with Tess his own departure from Fen fourteen years earlier - she becomes the link between the two men and allows Dunson a chance for redemption. They play cards - (she was to be employed as a card dealer for the gamblers):

Dunson: How'd you get that away from him?
Tess: I stole it...
Dunson: So you stole that bracelet. How did you get it?
Tess: Would you really like to know, Mr. Dunson?
Dunson: How'd you get it?
Tess: I got it in the rain eight days ago, before he took your herd across that river and left.
Dunson: I'm wondering whether to believe you.
Tess: I don't care whether you do or not.
Dunson: I believe that.
Tess: You wanna hear more?
Dunson: Go ahead.
Tess: It was raining. If it hadn't rained, I wouldn't be here talking to you. He wouldn't be here where you could find him to kill him. You still intend to kill him, don't you?
Dunson: Nothing you can say is gonna...
Tess: I didn't say anything...
Dunson: So he went off and left ya. I didn't give him that much credit. Are you in love with him?
Tess: I thought you'd ask that. Can a woman love a man who'd go off and leave her?
Dunson: Well, she, she shouldn't...
Tess: I wanted to go with him, but he had work to do. He had to get your cattle to market. Said I wasn't strong enough to go and nothing I could do or say to make him change his mind. But I wanted to go with him. I wanted him so much that...
Dunson: That you felt like you had knives stickin' in ya.
Tess: How did you know that? I suppose other people have felt that way before.
Dunson: They have.

Tess understandingly listens to Dunson's reason for wanting to kill Matt, his once-respected son, and how they grew to defy each other:

Tess: Now will you tell me something, Mr. Dunson?
Dunson: What?
Tess: Why do you want to kill him?
Dunson: Because he's a thief.
Tess: Do you think he thinks that?
Dunson: He should. I picked him up in the brush leading a cow. That's fourteen years ago. Taught him all I could. He knew what I was planning. Saw what I was building. He knew that someday, it'd all be his. His land, his cattle, the whole thing. Even talked of a woman as men will talk. A strong woman who could bear him sons, a woman like you.
Tess: Why did you want him to have a son?
Dunson: Because I built something. Built it with my own hands. And I can't live forever and live to see it grow. I thought I had a son. But I haven't and I want one.
Tess: I'm sorry for you, Mr. Dunson. Very sorry.

Dunson emphatically orders Tess to stand up and turn around so he can look at her [and assess her fertility], and then offers her half of his cattle empire if she will bear him a son - to pass on his heritage (and land) to the next generation. [Not wanting to lose another woman, Dunson quickly negotiates for the appealing Tess.] She agrees to bear a son for him if he will renounce his determination and change his mind about vengefully killing Matt:

Dunson: What would you say if, if I offered ya half of everything I own for a son?
Tess: Your son?
Dunson: You can have a son, can't ya? That's all that matters.
Tess: By Dunson out of Millay? Half of everything you've got.
Dunson: That's right.
Tess: I'll have your son, Mr. Dunson, if you'll stop now. Stop now and go back where you came from. I'll have your son.
Dunson: Yeah, I thought so.

Her unrealistic acceptance of his offer (she conceals a gun in her shoulder sling) is only an attempt at peacemaking - she soon reveals her love for Matt. Dunson recognizes the painful similarity between Tess and Fen - both women were left behind in the same manner. So, in remembrance of his lost love (Fen), he decides to allow her to travel along with him to Matt in Abilene, even though he refuses to give up on his murderous quest for Matt and his vow to kill her lover:

Dunson: When did you fall in love with him?
Tess: It was under a wagon, in six inches of mud. When did, when did you...when did you fall in love with her?
Dunson: Who?
Tess: The girl you told me about. The one you left, walked out on.
Dunson: 'I told you about'? Did he tell you...?
Tess: No, no, you told me. You knew how I felt when he left me. She must have felt the same way when you left her. That's right, isn't it? Or can't you remember?
Dunson: I can remember.
Tess: Oh I, I hope so, because, because I want you to think about it while I ask you something. I want you to think hard.
Dunson: What?
Tess: I want to go on with you.
Dunson: That won't do any good. Nothing you can say or do...
Tess: And though I know you told me that, oh please, I want to go with you. Please.
Dunson: All right.
Tess: Thanks. Thanks a lot.

The cattle drive moves on, although Matt suffers from doubts that his judgment is wrong - that there may be no railhead at Abilene and that Dunson will soon catch up:

One hundred days and in Matthew Garth's heart a growing fear that there was no railroad...

Shouts from the "point" drivers of the herd erupt when they hear a steam locomotive's whistle off-screen - it announces that Abilene exists at the end of the tracks after all. And then see the thick black smoke billowing up into the sky, proving that they are only a few miles from a railhead at Abilene, Kansas. Relieved and joyful, Matt successfully brings in the large herd of cattle all the way from Texas - the first rancher to use what will become known as the Chisholm Trail. Abilene townspeople are ecstatic to see the cattle ("We've been waitin' a long time for this") - the cowboys are instructed to drive the cattle straight down the main street of town to the stockyard.

Another page of the diary turns, marking an historic day in western history [the actual historical date for the opening of the Chisholm Trail was 1867]:

And history was written that day in Abilene, August 14, 1865, a day that marked completion of the first drive on the Chisholm Trail. Excitement and wild hilarity greeted the trail weary men and cattle as they poured into...

Cattle trader-buyer Mr. Melville (Harry Carey, Sr. - in his final Western film before his death in 1947) from "the Greenwood Trading Co. of Illinois" negotiates a contracted price for Matt's cattle. (They started the drive with over 9,000 head, losing six or seven hundred on the way.)

Only four or five hours behind them, Dunson comes upon the tracks where the cattle crossed to enter the town. The cattle clog the streets of Abilene - it takes many hours to herd them into the overflowing corrals in the stockyards. In Abilene that night, Mr. Melville settles at a "top price" of $21.00 a head, offering Matt an initial check for $50,000 dollars - made out to "Thomas Dunson." He tells Matt that he believes a celebration is in order for his men:

There's three times in a man's life when he has a right to yell at the moon: when he marries, when his children come, and when he finishes a job he had to be crazy to start.

Then after purchasing the cattle, Melville asks whether Matt's successful actions in bringing the herd to market will turn Dunson in his favor:

Melville: You gonna wait for Dunson, huh? I've been talkin' to some of your men. Isn't that check and the fact that you got here, isn't that gonna make any difference?
Matt: I don't think so, Mr. Melville.
Melville: I suppose I'm crazy but...
Matt: You want me to run away?
Melville: No, of course not. Couldn't, couldn't I talk to him?
Matt: I still have to talk to him after that.

When Matt steps into his Hotel Royale room for the night, he finds Tess waiting there for him. She warns that Dunson is camped two or three miles out of town, ready to enter town by sunup. Due to his battered pride, Dunson still plans to carry through on his threat to kill Matt ("He says he's going to kill you"). As she apologizes for accidentally being dressed in black mourning clothes, he crosses the room to approach her. He bumps into the hanging kerosene lamp, causing its swaying shadow to move back and forth over them [a premonition of Dunson's approach] and the room's walls as she nervously talks about his predicament the next day:

Tess: I know you've only a few hours, but listen for just a minute, that's all, and then I won't talk about it anymore. Just a minute. He hasn't changed his mind, Matthew.
Matt: I didn't think he would.
Tess: We saw the railroad and I thought, I thought it might make a difference, but it didn't. Nothing would. He's like something you can't move. Even I've gotten to believe it's got to happen - your meeting. I was gonna ask you to run but, no I'm not, I'm not. It wouldn't do any good. You're too much like him. Oh, stop me, Matthew! Stop me! (He covers her mouth and silences her. The moving shadow stops.) God bless you, Matthew. (He kisses her.)

Presumably, they are reunited and spend the night together after the scene dissolves away. The next morning, Matt emerges from the front door of the hotel into the bright sunlight looking relaxed and cool as he lights a cigarette. Tess stands next to Groot on the porch, as Matt leans on the horse railing and slouches amongst his men.

In the expected confrontation scene (a controversial, much-criticized ending for its flatness and lack of believability), bull-headed and intractable Dunson (with a group of ten men) rides through the cattle in the streets of Abilene to move toward Matt. After spotting Matt's surrogate father approaching, Buster rides ahead to alert him ("He's comin' in now"). When Dunson sees Matt in the distance, the camera tracks with him as he rides forward, dismounts and strides (actually plows or wades through them like water in a river) obliviously through the stray cows - the herd that took fourteen years to build up and nurture with his son. The soundtrack's driving music accentuates his rhythmic determination to reach his son. From the sidelines, Melville comments:

Melville: You know that young man [Matt] isn't gonna use his gun, don't ya?
Cherry: Yeah. But I haven't any such notions.

Almost immediately, after Dunson's contact with the herd - and its association with the Red River, there is violence. Cherry confronts the indomitable Dunson and wounds him in the left side, but is himself shot and crumples to the ground. When Dunson finally gets within firing range of Matt, he challenges him to draw, but Matt won't respond with his gun and risk a gunfight. Matt's eyes signal that he won't provoke a fight with a weapon:

Go on, draw. I said 'DRAW'! (Long pause) Then I'll make ya.

In the showdown, Dunson badgers his foster son. He begins shooting half a dozen shots all around the immobile, confident Matt - firing at his hat, at his feet, and nicking him on the right cheek. Frustrated by his son's steadfast refusal to fire back, Dunson cannot carry through his threat and kill Matt as he promised. His sense of morality and honor guarantees that he cannot kill a man in cold blood who doesn't intend on killing him first. Dunson throws his gun away and prepares to physically brawl with Matt:

You're soft! Won't anything make a man out of ya? (He seizes Matt's gun from his holster and throws it away.) You once told me never to take your gun away from ya. (He hits and punches Matt in the face several times.) You yellow-bellied, cotton-livered...

Eventually, Matt's temper breaks and he retaliates, punching back hard at Dunson's jaw - and the jab puzzles him momentarily. It evolves into a brutal, savage, monumental fistfight. Groot cheers the resolution of their brawling battle:

It's all right. For fourteen years, I've been scared, but it's gonna be all right.

The two men slam each other into one end of a chuck wagon, sending pots and pans clattering to the ground - similar to the incident that led to the deadly stampede. Disturbed by their senseless fighting, Tess fires a gun twice close to them to get their attention and then commands them to end their fighting and quit destroying each other. [Her feminine presence at the end of the film balances and corresponds to Fen's presence at the film's start.] By talking to both of them from her perspective, she reconciles Matt with his father in a new relationship:

Tess: (She fires once) Stop it. Stop it. Stop makin' a holy...(She fires a second time) Stop it I said. I'm mad, good and mad. And who wouldn't be. (To Dunson) You Dunson, pretendin' you're gonna kill him. Why, it's the last thing in the world you...(Dunson moves.) Stay still. I'm mad I told ya. (To Matt) And you Matthew Garth, gettin' your face all beat up and all bloody. You oughta see how, you oughta see how silly you look, like, like somethin' the cat dragged - STAY STILL - What a fool I've been, expectin' trouble for days when, when anybody with half a mind would know you two love each other. (To Dunson) It took somebody else to shoot ya. He wouldn't do it. Are ya hurt?
Dunson: No, just nicked the...
Tess: Then stay still. No, don't stay still. I changed my mind. Go ahead. Beat each other crazy. Maybe it will put some sense in both of ya. Go ahead. Go on. Do it! (After angrily thrusting her gun into the stomach of a cowhand/bystander, she marches off, disgusted by both of them.)

After hearing her sensible talk and intercession (and remembering - possibly - that he didn't listen earlier to lost fiancee Fen), Dunson realizes Matt's virtues as a son and advises him:

Dunson: You'd better marry that girl, Matt.
Matt: Yeah, I think I...Hey, when are you gonna stop telling people what to do?
Dunson: Right now. At least as soon as...
Matt: When?
Dunson: ...as soon as I tell ya one thing more.
Matt: What?

Then, in the last lines of the film, Dunson orders one last thing, promising to add Matt's initial to the Red River D cattle brand to make him a full partner in his cattle business. He draws the new brand in the dirt - a close-up of the brand ends the film as he announces that Matt has "earned" his manhood and become a full partner of his adoptive father. The first name initial, 'M', symmetrically balances out the surname, 'D', on the other side of the wavy, parallel lines that represent the Red River:

Dunson: When we get back to the ranch, I want ya to change the brand. It'll be like this, the Red River 'D' and we'll add an 'M' to it. You don't mind that do ya?
Matt: No. (They smile affectionately toward each other.)
Dunson: You earned it.