After a dissolve, Hammer is in almost the same position, but in a dominating clench and kiss with a lustful, forcefully aggressive Velda in the center of the room. [Her name is Velda Wakeman - Wake Man. Her endless, desperate goal is to awaken his own sexuality.] As his 'girl Friday' - a woman who tolerates the pimping or prostituting she must commit for him, she has brought a folder with information about science reporter Ray Diker (Mort Marshall) who lives on Flower St. - "a reporter on the news...who used to write a science column... dropped out of sight," but had called while Hammer was hospitalized. Typically, Hammer is more interested in Diker than Velda. He also suggests that she set up - with some of her familiar "sincerity" - another session with a 'lover boy'/adulterous husband since an incriminating audio tape of them was lost. While he lies on the couch and aloofly stares at the ceiling, his loyal aide, sexually-frustrated Velda describes her research findings about the mystery girl:

Velda: Christina Georgina Rossetti. Poetess, English, born 1830, died 1894. Your Christina was being held in that hospital for interrogation... What's the point of all this, if it's any of my business?
Hammer: She told me if I dropped her off at the bus station, I could forget her. But if she didn't make it, she said, 'Remember me.'
Velda: (seductively) So, remember her. She's dead. But I'm not dead. Hey, remember me.
Hammer: (non-chalantly) Yeah. I remember you from somewhere.

He cooly avoids her enticing, aggressively masculine sexual advances, either fearful of her or uninterested, and reminds her of other frame-up assignments that she must conduct with an adulterous 'Mr. Friendly' - he also amuses himself by listening to her seedy tapes:

Maybe he'll give you some of that nice dialogue again. That honey talk. That tape sure was NICE.

That night (at about 2:10 am), Hammer drives his Corvette convertible to Ray Diker's residence at 121 Flower St. in downtown LA. He is followed from a newstand (that sells newspapers with portentious headlines about a earth-shaking quake in Eureka in N. California) by an unidentified, shadowy figure (Paul Richards). At a popcorn vendor's stand, Hammer purchases a dime bag of popcorn. [There are continuity errors in this scene. The clock behind Hammer changes time rapidly.] The camera follows the hood's footsteps down the sidewalk, and his reflection is cast in a cigarette vending-machine mirror. When the pursuer pulls out a switchblade, they engage in a hard-hitting fight. Hammer sprays the man's face with his popcorn, disarms the attacker, subdues him with his fists, repeatedly knocks the man's head against a concrete wall until he's senseless, and then mercilessly punches the man down a steep flight of stone steps. From the bottom of the long row of stairs, the camera catches the attacker as he catapults down. After the pummeling, Hammer smiles.

Later, Hammer finds the Ray Diker residence and climbs the stairs of the Victorian house to the man's door. A closeup of Diker's frightened, bleeding, ulcerated, battered face appears in the window - the reason, apparently, why he "dropped out of sight." Fearless of consequences, Hammer learns Christina Bailey's address at the last place she lived - 325 Bunker Hill - and her mortal fear:

You were with her the night she died. She knew she was gonna get killed. She must have talked and told you...If you knew, you'd be afraid like she was afraid. Like I am. You'd better go.

Hammer follows the trail to Christina's former home. He assists an old Italian furniture mover (Silvio Minciotti) to carry a trunk - who laments about death and mortality, and people's inconstancy and lack of roots:

Sixty-three years, I live in one place - the house of my body. Move in when I born, move out when I die....People, they always move. They never stand still. They move from here, from there and move, and move all the time.

He is told by Horace, the building's superintendent, that the police have already been through Christina's apartment. "Her lease still has a month to go," but the police said it could be rented again. Hammer looks for posthumous clues - African masks hanging on the wall and built-in bookcases filled with books. Her radio is set to play classical music: Schubert's Unfinished Symphony ("She always had it tuned to that station"). Her bird cage is empty: "Her roommate let it die." Christina's room-mate, Lily Carver suddenly moved away, according to Horace:

She moved out a couple of days ago. All of a sudden, the middle of the night. Didn't say where.

In Christina's bedroom is an X-figured painting above the bed [recalling Christina's middle-of-the-road pose as she flagged down Hammer's car] and a book on the bedstand, Sonnets of Christina Georgina Rossetti. As Hammer leaves, the furniture mover whom he had helped divulges a secret - the current whereabouts of Christina's former roommate: "The other girl, the roommate of Miss Christina, she tells me not to say. Afraid she is. Like somebody's afraid to die. I moved her. I'll tell you where."

Following the lead and trail to Christina's roommate, he enters Lily's front hall corridor outside her room in the Jalisco Hotel - a high-angled, overhead shot envelopes him within the stairway, banisters and balustrades. In the residence of Lily Carver (Gaby Rodgers), the pixieish, waif-like blonde with closely cropped hair and a white, terry-cloth bathrobe with a sash reclines on a bed and has a gun pointed at his crotch. She is framed behind the bed post as she expresses her fear of the same men that pursued Christina. She assumes a vulnerable, high-pitched tone to her voice. [She has a striking resemblance to Christina in her trenchcoat. Although she is the alter-ego of Christina, she is a deceptive fraud - duping him with a false name, and by impersonating the dead woman's roommate - but Hammer doesn't know that until later.]

Lily: What do you want?
Hammer: I was with Christina the night she was killed. They tried to kill me, too. If you'd like, I'll show you the scars.
Lily: How'd you find me?
Hammer: I picked up the thread. Anybody could do it...
Lily: Christina was my friend.
Hammer: The bird in the cage. What happened to it?
Lily: (She lowers the gun) It was a nice bird. Used to eat out of my hand.
Hammer: You let it die. Why'd you let it die?
Lily: (She brings her hand up to her face and scratches her nose - her bent arm looks like a dysfunctional, pathetic bird wing of Christina's dead canary.) It reminded me of her every time it sang. She was a good kid. She was lots of fun. We worked together - a couple of jobs till she got sick. That's when I noticed that she started to change. You get on a merry-go-round. You think you can get off any old time. But then it starts going too fast. She was scared. She was more and more scared. She was afraid to go out. She'd go to the movies once in a while or out for groceries but never very far. And then the police came around. They asked questions, lots of questions. Then they took her away. After all, I had a feeling someone was watching the place. Then those men came.
Hammer: What did they want?
Lily: I didn't stick around to find out.
Hammer: Why was Christina so afraid? (Lily shrugs) It's all right, you can trust me.
Lily: I don't know.
Hammer: You want to get even for what happened to Christina, don't ya? I'll see what I can do.

Back at his apartment, another screened phone call (an unidentified caller) tells Hammer about the course of his investigation:

What does matter is that your work has been interrupted, your car wrecked, your life has been ruffled, to put it mildly. If you had not stopped to pick up Christina, not any of these things would have happened. So let's pretend you did not pick her up.

If Hammer pretends, his life "will go on as serenely as before." As a "token" of his intentions - and if Hammer stops his investigation - the gangster [later identified as conspirator/gangster Carl Evello] promises to reward him with a car the next morning in front of his apartment.

As promised, there's a black, shiny convertible on the curb the next day. Just in time, Nick is told to not start the ignition - the car has been planted with a rigged, explosive device ("torpedo") attached to the starter. And Hammer instinctively knows that the first "torpedo" is a precursor to a second, more deadly rigged mechanism. Back in the garage, Nick finds a trickier bomb device ("a sweet little kiss-off") set to explode at a high rate of speed. According to Nick, it explodes when they go "Va-va-Voom" - a portent of future disaster.

Hammer strides through a door into Velda's apartment with a black-and-white checkered tile floor - metaphoric of the chess game being played within the film. In an adjoining room with mirrored walls, a confusingly-reflected Velda (in a black and white striped shirt and black leotards) exercises and glistens with sweat in a ballet studio with classical music playing on a phonograph. Next to an exercise bar, she stretches one limber leg and arm up and down. As he leans back languidly while smoking, he instructs her to cancel her latest errands that squeeze big payoffs from husbands and wives in messy divorce and infidelity cases. She figuratively warns of the possible consequences of his risky investigation - a little thread will lead to a string and then to a rope by which he will be hanged:

Hammer: We're gonna steer away from these penny-ante divorce cases for a while. I've got a line on something better. That girl I picked up was mixed up in something big.
Velda: And a cut of something big could be something big.
Hammer: I want you to find out all you can about her.
Velda: (She breathlessly twirls playfully around a black, floor-to-ceiling, phallic-symbol pole and Hammer follows her spinning, teasing action with his eyes.) First, you find a little thread, the little thread leads you to a string, and the string leads you to a rope, and from the rope you hang by the neck. What kind of a girl was she, this friend of yours, Christina?

In the meantime, according to Velda, Ray Diker has phoned with additional names that Hammer might want to check up on:

LEOPOLD KAWOLSKY
HARVEY WALLACE

OVER BOMBA CAFE, CAHUENGA STREET

NICHOLAS RAYMONDO
CARMEN TRIVAGO

HILLCREST HOTEL, TEMPLE STREET

Trying to inflame his passion, Velda purrs into Hammer's ear, but he non-chalantly pays no attention, takes in her warmth without reciprocating, and reacts with a non-sequitur. She looks at him with sexual dissatisfaction - her masquerading as a hooker has no effect on him, although it is paradoxically quite effective on adulterous husbands in their profession.

According to Velda, two of the men, Kawolsky and Raymondo, were killed under suspicious circumstances, similar to Christina's death:

Velda: ...but under any other name, would you be as sweet?
Hammer: Kawolsky.
Velda: Kawolsky. He was a professional fighter. His first name was Lee. Couldn't get anything on Raymondo. Don't know what he was.
Hammer: Why do you keep saying 'was'?
Velda: They both knew your Christina. They both died the same way she did.
Hammer: How's that?
Velda: The way you almost died. Traffic accident? One fell out of a cab, and the other was run over by a truck.
Hammer: Who's Carmen Trivago?
Velda: Carmen Trivago. A poor man's Caruso, an unemployed opera singer in search of an opera. Raymondo's friend.
Hammer: And who's Harvey Wallace?
Velda: He drove the truck that ran over Kawolsky.

Subsequently as he drinks the man's beer and joins the family at dinner, Hammer briefly questions truck driver Harvey Wallace (Strother Martin) about the truck 'accident' that killed Kawolsky. Wallace concurs that "maybe he was pushed."

In a second interview regarding Kawolsky's suspicious death, Hammer travels to a boxing gym - a sequence that opens with a man noisily punching a bag toward the camera. A tall, broad-shouldered black figure moves by and the camera follows him down the stairs - where it picks up Hammer climbing up the stairs as he saunters over to Eddie Yeager (Juano Hernandez), the black fight manager with an upwards-pointing cigar in his mouth. Hammer suspects that Yeager's next upcoming fighter Kid Nino will throw his next evening's bout "like you sold out all the others...wait until the odds build up until you can't resist."

When Hammer asks a concluding question about Lee Kawolsky, Yeager's ex-fighter who "was killed in an accident but it wasn't really an accident," Yeager's cigar drops in his mouth as an expression of his fear. Even though Yeager was recently intimidated, threatened, and told to shut up or die: "They said they'd let me breathe," he gives Hammer the names of the two hoodlum strong-arms, Charlie and Sugar, who do dirty-work for a local gangster named Carl Evello.

The next scene opens in blackness - until the pool-side, black-attired hostess walks away from the camera. Next to Carl Evello's (Paul Stewart) outdoor, elegant pool, Charlie Max (Jack Elam) and Sugar Smallhouse (Jack Lambert) are bickering with each other while playing gin rummy and listening to the horse races on the radio. [The poolside shot was deliberately created to frame together three top heavies in post-war Hollywood films - Elam, Lambert, and Stewart.] Hammer drives his sports car into the Doheny mansion driveway, followed closely by an amorous, nymphomaniac blonde named Friday (Marian Carr). After she is assured by the magnetic, alluring playboy that he doesn't bite, she kisses him on their first meeting and then compliments him: "You don't taste like anybody I know":

Hammer: How do you do, ma'am?
Friday: How do I do? Cra-zy. (They kiss)
Hammer: Don't be afraid. I won't bite.
Friday: You don't taste like anybody I know. That's all right. In fact, it's wonderful. Come on, Crazy. Seconds?
Hammer: OK. (They kiss again)
Friday: You sure we haven't met before?
Hammer: Never.
Friday: Who are you?
Hammer: Who am I? Who are you?
Friday: I'm Friday. I'd have been named Tuesday if I'd been born on Tuesday. I'm Carl's sister, half-sister. Same mother, different father. You know, you're not like the others - Carl's friends, I mean.
Hammer: Maybe that's because I'm not his friend.
Friday: Oh, wonderful. Then you can be my friend, all my nothing-to-do-with-Carl.

In the mobster's mansion, Hammer teaches an amorously-inviting Friday how to be unresponsive, cold and callous - like he is - by saying 'no':

Friday: Will you be my friend?
Hammer: What do I have to do?
Friday: I want to be a close friend. Ask me something.
Hammer: And no matter what it is, the answer's 'yes', isn't it?
Friday: Maybe.
Hammer: Let's see how good you are at spelling. Can you spell the word 'no'?
Friday: N - O spells 'no.'
Hammer: That's a good girl. Now you practice saying that. Because one of the best ways to be friendly is to know when to say no.

He is only there for information and asks whether her brother Carl wears blue suede shoes - she replies: "Hardly. He's more the black moccasin type." In the pool bath house, Hammer snoops around and surveys the shoes on the floor - in a camera pan from right to left, he finds no blue suede shoes. When Evello's thugs try to put him out of action, Hammer subdues Sugar with a judo chop. The mobster decides he will talk to Hammer in the house, not exactly knowing what Hammer is searching for - so Hammer explains (using Velda's terminology):

Yesterday, I was looking for a thread. Today, I'm looking for a piece of string.

Evello offers him a payoff: "What's it worth to you to turn your considerable talents back to the gutter you crawled out of?" Hammer bargains for a high fee: "I set my fee according to the case, and the longer I look at this one, the higher it gets." But then, the buy-off offer is withdrawn: "Suddenly, it's too late." Hammer realizes that Evello works for some higher-up.