When the children return from their unsuccessful venture, their father questions them about their secretiveness about where they went, and for being late for dinner. Marta makes up an impossible excuse: "We were berry-picking," but that's impossible: "It's too early for blueberries." For their escapade and deceitful alibis, they are denied dinner. They are reminded of Maria's cure for feeling better - singing "My Favorite Things," but they don't feel any change - until they hear Maria's voice harmonizing with theirs. She has returned and happily joins in. They tell her the impending, life-changing news that the Captain will be marrying the Baroness: "The most important thing is that father is going to be married...to Baroness Schraeder."

The Captain walks down the steps to greet Maria and to ask why she left - but she is devastated and can't answer. She decides to stay only until he finds a new governess:

Captain: You left without saying goodbye, even to the children.
Maria: It was wrong of me, forgive me.
Captain: Why did you?
Maria: Please don't ask me. Anyway, the reason no longer exists.
Baroness: Fraulein Maria, you've returned. Isn't it wonderful, Georg?
Maria: May I wish you every happiness, Baroness? And you too, Captain. The children tell me you're to be married.
Baroness: Thank you, my dear.
Captain: You are back to, uh, stay?
Maria: Only until arrangements can be made for another governess.

That evening in a blue dress, Maria walks near the lake and gazes up at the night sky, thinking about her life and its dilemmas. From his balcony's terrace, the Captain also appears and looks down at her - connected across the distance. Elsa follows toward him and rattles on about what wedding gift she should give him: "...I do want you to have some little trifle for the occasion. At first, I thought of a fountain pen but you've already got one. And then, I thought perhaps a villa in the south of France, but they are so difficult to gift wrap...And where to go on our honeymoon - now that is a real problem. I thought a trip around the world would be lovely. Yet I said, 'Oh Elsa, there must be someplace better to go.'" After some mutual soul-searching, they both decide to gracefully break off their engagement:

Captain: It's no use, you and I. I'm being dishonest to both of us and utterly unfair to you. When two people talk of marriage...
Elsa: No, don't, don't say another word, Georg, please? You see, uh, there are other things I've been thinking of. Fond as I am of you, I really don't think you're the right man for me. You're much too independent and I need someone who needs me desperately, or at least needs my money desperately. I've enjoyed every moment we've had together. I do thank you for that. Now, if you'll forgive me, I'll go inside, pack my little bags, and return to Vienna where I belong. And somewhere out there is a young lady who I think will never be a nun.

The Captain readily joins Maria by the pavilion, and asks two questions:

• "Why did you run away to the Abbey?"
• "What was it that made you come back?"

According to Maria, she "had an obligation to fulfill and I came back to fulfill it..And .I missed the children." He explains that "nothing was the same" while she was away and "it'll be all wrong again" after she leaves again. He attempts to persuade her to change her mind and stay longer. And then he tells her that his engagement to the Baroness is off: "There isn't going to be any Baroness...well, we've, uhm, called off our engagement, you see...Well, you can't marry someone when you're in love with someone else, can you?" He holds her tenderly by the chin and draws her lips nearer for a kiss. Relieved, Maria has had her prayers answered:

Maria: "The Reverend Mother always says, 'when the Lord closes a door, somewhere he opens a window'."
Captain: "What else does the Reverend Mother say?"
Maria: "That you have to look for your life."
Captain: "Is that why you came back?" (She nods) And have you found it Maria?
Maria: "I think I have. I know I have."
Captain: "I love you."
Maria: "Oh, can this be happening to me?"

As they are reunited and now free to express their love, they both sing: "Something Good" - about being rewarded for something good they did in the past:

(Maria) Perhaps I had a wicked childhood, perhaps I had a miserable youth
But somewhere in my wicked, miserable past, there must have been a moment of truth
For here you are standing there loving me, whether or not you should
So somewhere in my youth or childhood, I must have done something good
Nothing comes from nothing, nothing ever could
So somewhere in my youth or childhood, I must have done something good.

(Captain) For here you are standing there loving me, whether or not you should
(Maria) So somewhere in my youth or childhood, I must have done something good.
(Both) Nothing comes from nothing, nothing ever could
(Maria) So somewhere in my youth (Captain) or childhood, (Maria) I must have done something, (Both) something good.

In a room off the Abbey cloister with wedding bells pealing in the background, the nuns help prepare Maria's satiny wedding gown. They escort her to the cathedral gate, where she enters as the black-cloaked nuns remain outside and separated. The three young von Trapp girls serve as bridesmaids, and the Captain appears in full uniformed regalia at the front of the main Salzburg Cathedral for the religious marriage ceremony.

Outside, in a transition that conveys a short passage of time following the marriage, and the peaceful German Anschluss (annexation) of Austria [in March of 1938], Nazi troops march and assemble in the Salzburg Square under large red Nazi swastika banners. Herr Zeller, now a high-ranking Nazi official, is driven to the folk festival's rehearsal, where he appears aggravated that "the only one in the neighborhood not flying the flag of the Third Reich since the Anschluss" is the Captain. Zeller wants to know from Max when the Captain will be returning from his month-long honeymoon trip.

According to Zeller, the Captain will be expected to serve under the Nazis: "When he does return, he will be expected to fill his proper position in the new order." But the festival concert will be held that evening as originally scheduled: "Nothing in Austria has changed. Singing and music will show this to the world. Austria is the same." Young Marta thinks "maybe the flag with the black spider on it makes people nervous." Rolf has become indoctrinated into the Party of the Third Reich and delivers a telegram (from Berlin) for Liesl to transmit to her father. He boasts about the omniscient Nazis: "We make it our business to know everything about everyone." He ignores her romantic invitation: "I'm now occupied with more important matters. And your father better be too if he knows what's good for him."

Upon his return to his villa, the Captain pulls down the Nazi banner hanging there. Disgusted, he rips it into two. The children excitedly invite Maria to attend the festival in the evening, but the Captain again refuses to have them compete in public. Max is disturbed because "if the children don't sing at the festival, well, it will be a reflection on Austria." Maria gives motherly advice to Liesl, now rejected by Rolf, about what happens when a person stops loving you:

You cry a little and then you wait for the sun to come out. It always does.

To buoy Liesl's mood, she reprises a variation of "You Are Sixteen, Going on Seventeen," suggesting that she wait a year or two.

The telegram from Berlin (from Admiral von Schreiber of the Navy of the Third Reich) offers the Captain a commission to join the German Navy, but the former Navy officer adamantly refuses to serve under Hitler: "I've been requested to accept immediately and report to their naval base at Bremerhaven tomorrow...To refuse them would be fatal for all of us. And joining them would be unthinkable." His plan is to "get out of Austria - and this house - tonight" without alarming the children. During the family's nocturnal attempt to flee the country that evening after packing, the von Trapps silently push their car past their house. It is thought that by the time the von Trapps have been announced to sing in the music festival, they'll "be over the border." But they are detained by the Nazis outside their own gate. Zeller offers an escort to the Salzburg show and then afterwards to Bremerhaven to force the Captain to accept his commission. To his children's astonishment, their father convinces the Nazis that they are costumed in readiness for their performance in the musical festival.

Nazi guards watchfully surround the open-air amphitheatre during the Salzburg Folk Festival. As a farewell song dedicated in tribute to his "fellow Austrians," the Captain patriotically reprises the "love song" "Edelweiss."

I know you share this love. I pray that you will never let it die.

During the singing of the song, his voice cracks, and Maria steps in and encourages the entire audience to sing-along in an act of bold freedom that displeases the Nazis. While the judges are evaluating the performances of the competition, Max uses coded language to tip off the von Trapps to escape:

The festival competition has come to its conclusion, except of course we don't know yet what that conclusion will be. And while the judges are arriving at their decision, I have been given permission to offer you an encore. This will be the last opportunity the von Trapps will have of singing together for a long, long time. Even now, officials are waiting in this auditorium to escort Captain von Trapp to his new command in the naval forces of the Third Reich. (The crowd murmurs in reaction.) And so, ladies and gentlemen, the Family von Trapp again to bid you farewell.

The family's encore is "So Long, Farewell," an opportune song that allows each of the members of the family to leave the stage. The results of the judging are announced by Max at the end of the show. The von Trapps are awarded first prize, "the highest honor in all Austria," but they fail to appear after two fanfares. A Nazi guard runs out of the entryway crying: "They're gone!" Nazi cars speed to the Abbey's convent, where the family has fled and is being hidden by the Reverend Mother in the dark crypt area. A search commences, but the fugitive family cannot be found. Because the borders are closed, the Captain decides to flee with his family toward the Austrian mountains in the convent's car, and then proceed on foot. The Reverend Mother blesses them: "I lift up mine eyes into the hills, from whence cometh my help...God be with you."

Rolf, one of the Nazi guards, slyly remains behind as the others search the roof area, and he discovers them as they emerge from their hiding places. As the family escapes to the convent's car, the Captain remains behind and challenges the pistol-wielding young lad:

You're only a boy. You don't really belong to them...Come away with us before it's too late...You'll never be one of them.

Although the Captain safely removes the revolver from the boy's hands, Rolf summons the other officers. The entire family speeds off towards the mountains. Zeller and his men hear a car racing away and rush out to their vehicles, but they can't get them to start. By an upstairs window, the sisters confess to the Reverend Mother that they "have sinned" - they exhibit vital car parts from under their robes.

The von Trapps are last seen climbing the Austrian mountains to freedom in Switzerland, where they can perform to the world. A chorus sings the finale of "Climb Ev'ry Mountain."