She's dead, blown up in a dynamited car, dynamite meant for him. Lang's eyeline match captures the noir mood of alienation and more importantly devastates the audience as he closes it off with a medium close up of Ford, eyes watered. Bannion was investigating the suicide of Tom Duncan and the evidence had lead him to the mobster, Lagana. Lagana's men took the corruption of the mean streets and spilled them into the detective's home, destroying his domestic space. Angry and alienated from humanity, the invasion spins Bannion in a new direction of personal revenge.
But revenge in this film rings hollow. Whereas many noirs contain the tradition of the femme-fatale, the deadly spiderwoman who destroys her man and his family and career, The Big Heat inverts this narrative paradigm, making Ford the indirect agent of fatal destruction. All four women he meets--from clip joint singer, Lucy Chapman to gun moll Debby--are destroyed.
Lucy is destroyed because Bannion refuses to take her story seriously. She was Tom Duncan's lover, and Bannion sees her as a no-good party girl and refuses to go give her any respect. When he hears of her relationship with Duncan, he separates himself, sliding across the club's bench seat and surly saying, "That sounds very cozy." He mistakenly judges her. "You trying to use us for a shakedown." "Me?" Lucy says incredulously. "At least I'll show she's a liar." Lucy is right--Mrs. Duncan lies, but because of Bannion's class prejudices, he is taken in by Mrs. Duncan's performance. Earlier Mrs Duncan had won over his sympathy. As she sat by a three-way mirror, Ford knocked at the door. Suddenly her face turned from a mean scowl to a sudden propriety, and her voice adopted the grieving quaver of a recent widow. Eventually, because Lucy's had talked to Bannion, she is killed--her body found on a county road, burned, tortured, by cigarette butts. Her death motivated Bannion to pursue Duncan's death with more rigor.
Mrs. Bannion is destroyed by Bannion's aggressive masculinity. Following a lewd, threatening phone call at his home, Bannion barges into Lagana's estate and insults the mobster, by talking about Lucy Chapman's murder: "Yeah, it was an old-fashioned killing, prohibition kind. . . ." Lagana, sits calmly behind the desk, quietly enraged at the prohibition reference. Ford pushes his luck, "What's a matter, you think I live under a rock or something? You creeps have no compunction about phoning my home talking to my wife like she was--" George, Lagana's strong arm, enters and Ford with a right cross, a left, and a two-handed smash buries him. "You want to pinch-hit for your boy, Lagana?" Ford challenges. Lagana, threatened, eventually responds with two other pinch-hitters: Vince Stone (Lee Marvin in one of his deliciously dangerous roles) and Larry Gordon are hired to kill Bannion. Unfortunately, Gordon gets a little sloppy, his bombing targeting the wrong Bannion.
Bertha Duncan is destroyed by Bannion's doppelganger, Debby (Gloria Grahame in her greatest role). Bannion's investigation leads him to reassess Bertha Duncan. Tom Duncan had written a suicide note in which he named names. Bertha found it and used it to blackmail Lagana and Stone. Bannion wants that note to go public, so he threatens Bertha: "If anything happens to you, the evidence comes out." He pushes her into the mantle. "With you dead, The Big Heat falls." He starts to strangle her, but stops as the cops arrive. He then returns to Debby and tells her how close he came to killing Bertha. "I wish I had," he says. Debby says that he couldn't do it, and then he runs to take care of his child. As he leaves he throws a gun on the bed, "Keep that for company" he says, indirectly giving her the means to kill Duncan. And that's what she does, becoming an extension of Bannion's will. She visits Bertha--they're both in minks, as Lang layers his doppelgangers "I never felt better in my life," Debby says, after she shoots her. Her gun falls on the floor and Lang makes an implicit moral comment through a dissolve. The gun is overlapped with an image of Bannion alone on the street, clearly linking Debby's action with Bannion's hidden desire.
Finally, Debby's actions, too have their destructive consequences. Earlier Vince Stone had splashed hot coffee in her face following her information rendezvous with Bannion. At the end of the film, Debby returns the favor, scalding Vince, and as she brags about her moral reformation, "The lid's off the garbage can and I did it," Vince shoots her in the back. Before she dies, she heals Bannion, opening him up to feeling. "Remember how angry you got when I asked you about your wife," she says, and Bannion eloquently speaks about his past domestic life: "Kate was a sampler. She'd take sips of my drink and puffs on my cigarette--" Debby's death restores Bannion and our moral order, but Lang's ending is cautious and grim. Later, Bannion picks up the phone: there's a hit and run over on South Street. As he exits, we are reminded of the circularity of crime and its cost. A huge poster on the office wall reads, "Give Blood, Now." It seems that the women in this dark noir have given more than their fair share.