One night, private detective Mike Hammer is driving home to Los Angeles when he is stopped by a woman standing in the highway. Although Mike upbraids the woman, he gives her a ride. As they drive, the panicked woman, who is wearing only a trenchcoat, asks Mike to drop her at the nearest bus stop. Before Mike can learn more, they are stopped at a roadblock, and the police reveal that they are looking for a woman who escaped from a nearby sanitarium. After Mike bluffs his way past the officer, the woman, named Christina, admits that she is the escapee, but insists that she was being held prisoner at the sanitarium. When they stop at a gas station, Christina gives the attendant a letter to mail and looks relieved. Mike is intrigued by Christina's demeanor and her plea to remember her if anything should happen. Just then, a car blocks their way and Mike is knocked unconscious by the occupants. When Mike awakens, he hears Christina scream as she is being tortured, but because he is lying face-down, he cannot identify his captors, although he does notice that one wears a distinctive pair of shoes. After Mike passes out again, he and the now-dead Christina are put into his car, which is pushed over a cliff to make it look like they died in an accident. Mike jumps from the car just in time, however, and three days later, is wakened in the hospital by his devoted secretary and girl friend, Velda Wickman. Mike's friend, police captain Pat Murphy, is also happy to see him recovering. When Mike leaves the hospital, he is detained by federal agents, who question him about Christina. Mike refuses to divulge any information, and after he is released, Pat warns him not to pursue the matter. At his apartment, Mike tells Velda that they are going to investigate anyway, and she reveals that a man named Ray Diker called while he was in the hospital. Their conversation is interrupted by Pat, who revokes Mike's private detective license and gun permit, then dismisses Mike's...