One night while driving down a dark road near Los Angeles, private detective Mike Hammer (Ralph Meeker) nearly runs down a young woman named Christina (Cloris Leachman) standing in the road who begs for a ride. Hammer gives the blonde a ride thinking she may be an escaped lunatic since she is only dressed in a trenchcoat. When they confront a road block, Hammer covers for the young woman after she gives him a story about some mysterious characters who are chasing her. Hammer shrugs it off until a car cuts them off and several shady men grab them, kidnap Christina and run Hammer off a cliff destroying his car and putting him in the hospital. When Hammer comes around he is bent on vengeance but more on solving the mystery of who these guys are and why they killed Christina. So he begins to investigate the woman's past, based on a clue that she left before she died. Hammer turns to his affectionate assistant Velda (Maxine Cooper) and Nick (Nick Dennis), his garage mechanic to track down helpful information and she finds the addresses of Christina's roommate Gabrielle (Gaby Rodgers), scientists, and art dealers who all have an interesting connection to a group of thugs composed of Carl Evello (Paul Stewart), Charlie Max (Jack Elam) and Sugar Smallhouse (Jack Lambert) and a mysterious box that holds the key to the mystery. An evil doctor named Soberin (Albert Dekker) catches up with Hammer and a finale brings about tremendous happenings.
This is a more detailed Synopsis.
The movie opens with a woman, Christina Bailey (Cloris Leachman) running down the middle of a street wearing just a trench coat. It is dark and she tries to flag down several cars with no luck. Finally, in desperation, she blocks the street forcing Mike Hammer (Ralph Meeker) to swerve his sports car into the soft shoulder of the road. Very annoyed, he tells her to get into his car. He drives down the road. Credits roll in reverse from top to bottom to the Nat King Cole song, "Rather Have the Blues" playing on the radio. Christina keeps looking back. She tells Mike she's heading for Los Angeles. They come to a road block. "A woman escaped from an asylum upstate", is the reason given by the police. Mike tells the officer his wife was asleep, explaining her appearance in "his" trench coat in an open top roadster. Mike stops at a service station. The mechanic finds and dislodges a shrub caught in the front wheel. Christina uses the bathroom, and then asks the mechanic (Robert Sherman) to mail a letter for her. They resume their journey. She tells Mike if they don't make it to her bus stop to "remember me." A large black Cadillac pulls out and blocks the road. Three men get out. Next we hear screaming and see a woman's legs twitching. Christina is being tortured with a pair of pliers (discreetly off camera). Mike is unconscious on a bare metal bed spring mattress. Mike awakens and learns Christina is dead. He and Christina are put in his car and pushed over a cliff. He is thrown clear before the car crashes and burns. The Cadillac pulls away.
Mike wakes in a hospital room to the faces of a nurse (Mara McAfee) and his secretary, Velda Wickman (Maxine Cooper). The doctor enters and tells Lt. Pat Murphy (Wesley Addy) he has five minutes. Pat asks Mike what happened. Sometime later Mike is discharged. As he leaves with Velda, he is immediately detained for questioning by the Interstate Crime Commission. Pat waits outside the hearing room. FBI agents (Robert Cornthwaite and James Seay) ask Mike about his business. They are investigating Christina's death. Mike deduces Christina was involved "in something big." He sees a potential business opportunity.
Mike takes a cab to see his mechanic, Nick (Nick Dennis). He is told the car was totaled, and that a couple of tough guys were looking for him. The tough guys are waiting outside Mike's apartment building when he gets home. He carefully approaches his apartment door, expecting someone waiting to ambush him, but the place is empty. The phone rings and the answering machine picks up; it is Velda, she tells him she is on her way over. Velda arrives, followed shortly by Pat--official business. Pat lets himself in. He revokes Mike's Private Investigator license and his gun permit. Mike asks Pat about a science reporter, Ray Diker. Mike and Velda discuss a return to their usual business--divorce investigations.
In a different sports car, Mike is on his way to visit Ray Diker (Mort Marshall). He is followed by an attacker (Paul Richards). Mike gets the drop on him and easily disarms and dispatches the guy. He proceeds to Diker's apartment. It is clear the man is terrified as he shows signs of an earlier beating. He tells Mike he's afraid, just like Christina. He provides Mike her last name and address. Mike drives to Christina's last known address where he gains the confidence of an old furniture mover (Silvio Minciotti). He gives Mike the current address of Christina's roommate. The apartment manager, Horace (James McCallion) shows Mike the apartment. There he collects a volume of poetry by Christina Rossetti. Mike drives over to see the roommate, Lilly Carver (Gaby Rodgers). She greets him with a gun. They talk. She tells Mike about Christina and the night she was taken away.
In his apartment, Mike gets a phone call. He lets the answering machine screen his call. A man's voice recounts the events to date; Mike picks up the phone to talk to the stranger. Mike is told if he "forgets" about events he will be rewarded. The next morning a brand new Corvette is parked in front of the building. Nick sees it first and gets in; he intends to drive it around the block before Mike gets there. Mike warns him in time not to touch the car--it is wired with explosives. He finds and removes the bomb, but Mike tells Nick to drive slowly over to the shop to find the second bomb. Mike asks Nick to discreetly find out who planted the bombs. This little task will prove to be a fatal one.
Mike stops at Velda's apartment to tell her the divorce business is a little too small time; he has something better, "That girl I picked up was mixed up in something big." Velda tells Mike that Diker called and left two names and contacts. Leopold Kowolsky / Harvey Wallace and Nicholas Raymondo / Carmen Trivago. Velda tells Mike that Kowolsky was a pro fighter, but she had nothing on Raymondo. She emphasizes "was" as they both knew Christina and are both dead.
Mike questions Harvey Wallace (Strother Martin) at home while he and his family are eating dinner. Wallace finally admits Kowolsky was pushed in front of his truck and killed. Next on his list is the gym where Kowolsky trained. He sees an old friend and trainer, Eddie Yeager (Juano Hernandez). Mike inquires about Lee Kowolsky. Eddie is shocked and scared. He tells Mike he has "forgotten". Two men, Charlie Max (Jack Elam) and Sugar Smallhouse (Jack Lambert) told him if he said anything about Kowolsky he would be killed. Mike calls Pat at police headquarters and asks who Max and Smallhouse work for. He is told Carl Evello (Paul Stewart).
At the Evello home, Max and Smallhouse are playing cards and Evello is sitting by the pool having a drink and playing solitaire. Mike arrives in his new car. Evello's half sister, Friday (Marion Carr) is right behind him in her car. She kisses Mike, and then introduces herself. They go into the house and have a drink. Friday is what used to be called "a very loose woman." Evello recognizes Mike Hammer and sends Charlie and Sugar to the pool house to see him. Expertly wielding a sap or blackjack, Mike coldcocks Sugar. Charlie is so surprised he exits quickly and quietly back to see his boss. Evello tells Friday to, "send him into the house." They talk. Evello admits to placing the explosives in Mikes new car, "I'll admit that was a little crude...We keep underestimating you." Their meeting ends on an ominous note--play ball or die.
Mike drives over to see Carmen Trivago (Fortunio Bonanova). Like all his other leads, this one is scared. He tells Mike, "I know nothing." He does manage to get that whatever "it" is, it is small and can be hidden. That evening he returns to see Lilly Carver; she is hiding on the stairs and tells Mike, "they came again last night, I hid in the basement." He takes her back to his apartment. Nick has done a little investigating earlier in the day, so when Mike drops by he tells him he has some information about the car bomb. Mike still needs to secure Lilly Carver at his place, so he tells Nick he will be back to talk. Nick crawls under a car to work and is killed by a man we never see. Mike gets Lilly to his apartment and tells her to lock the door and not to answer the phone. Mike drives back to Nick's garage and finds another mechanic Sammy (Jerry Zinneman) holding Nick's dead hand and sobbing. Mike leaves when he hears a police siren.
Mike drives to Velda's apartment; They kiss. She asks, "what kind of trouble are you in this time?" He tells her Nick is dead. She gives Mike another lead, Dr. Soberin. The next day Mike stops at a nightclub and gets very drunk. The bartender wakes him and says, "They got Velda." Mike drives back to the gas station and talks to the attendant. He asks if he remembers who to whom Christina addressed her letter. The attendant tells him, "Some joker named Mike." He goes to his office and opens the letter. It only says, "Remember Me." Charlie Max and Sugar Smallhouse are there to greet him. Sugar returns the favor with a blackjack of his own. They take Mike to a beach house in his own car. Mike makes a run for it when he gets the chance, but Charlie and Sugar give him a good beating for his attempt. He wakes tied securely to a bed. A man tells Mike he will die, but he can save Velda. The man drugs Mike with sodium pentothal then exits the bedroom. Mike mumbles under the influence of the drug. Carl Evello comes in to question him, but gets nothing. Mike manages to work one hand free from the ropes. He calls out and Carl returns. He lures Carl over and knocks him out. Mike pretends to be Evello and summons Sugar in to kill Mike. Sugar enters the darkened room and stabs his boss, thinking it is Mike. Mike kills Sugar and escapes.
Mike returns home; Carver is there and dressed. Mike picks up the book of poetry and reads the sonnet "Remember Me." He gets a clue that something may have been inside of Christina. Mike and Lilly visit the coroner's office. The Autopsy Surgeon, Doc Kennedy (Percy Helton) is corrupt and wants money for the key he found in Christina's stomach. Mike pays him, but the doctor tries to welch on the deal. Mike smashes his hand in a desk drawer to get the key. It has HAC stamped on it. They drive over to the Hollywood Athletic Club. Mike has to get tough with the attendant (Leonard Mudie). The attendant tells him it is a locker key and escorts Mike to Nicholas Raymondo's locker. Inside the locker is a leather covered box that Mike notices is very hot to the touch. He opens it slightly and an intense light shines from it. It burns his wrist. He tells the attendant not to touch it. When Mike returns to the car, Lilly Carver is gone.
At his apartment, Pat and three policemen are waiting for his return. Pat demands the key. Mike confronts Pat with Pat's complicity in all the deaths and his inability to protect all the people who were killed. When he mentions Carver, he is told Carver was killed over a week ago. Then who was that woman? Pat notices the radiation burn on Mike's wrist. Mike gives Pat the key. The police depart. Mike calls the Hollywood Athletic Club, but there is no answer. The locker is broken open, the attendant is dead and the box is missing. That evening Mike makes another call on Ray Diker. He gets another name, William Mist, owner of Mist's Gallery of Modern Art. Mike breaks in but Mist (uncredited) takes a hand full of sleeping pills, prescribed by Dr. G.E. Soberin. Mist is unable to tell Mike anything, despite being slapped around. Mike does manage to get Soberin's location through his answering service. On a hunch he goes to the beach cottage and recognizes the place from his encounter with Evello, Charlie and Sugar.
Dr. Soberin (Albert Dekker) is packing to leave. He talks to Lilly Carver, whose real name is Gabrielle and we learn she was employed by Soberin to get the key from Christina and keep an eye on Mike Hammer. Gabrielle wants her share, half, and before Soberin leaves. When Soberin brushes her off she kills the doctor. With his dying breath he begs her not to open the box. Mike enters the room and gets a bullet for his trouble. He demands to know where Velda is located. Gabrielle opens the box and is immediately consumed by fire. Mike comes to and exits the room. He finds Velda in a locked bedroom, frees her, and they leave the house. They run along the beach, occasionally looking back at the strobe effects lighting up the house and beach. They make their way into the surf as the house explodes. We close with Mike and Velda in the surf watching the house disintegrate.