Mannix has finally quit the detective agency for good and is out on his own. The second season begins when Mannix encounters a deaf woman who has witnesses a criminal talking at a pay telephone, discussing a kidnapping. She has made out certain key words because of her ability to read lips. Mannix gets her to remember enough of the conversation so that he can proceed in his investigation. The detective finds a rich man who says his wife has been kidnapped. It turns out the rich man has really hired the criminal to kill his wife and make it look like a kidnapping - and...
Charlie Anderson, a former policeman who once saved Joe Mannix's life, hires the detective when his wife has run off. The wife is somebody else Charlie met while a policeman - a one-time prostitute who went straight. Charlie now is a security guard at a air cargo facility. One test run has gone badly, thanks to Charlie being suspicious of hoods. Mannix, after being beaten by hoods, learns in the hospital that Charlie and his wife are together again and that he's off the case. Mannix is determined to find the truth.
Joey, a young man who helped Mannix out on a previous case, shows up in the detective's apartment, injured from a beating. Mannix hides Joey and gets a call out to the police just before the apartment is overrun by hoods. Mannix is beaten and when he wakes up, Joey is gone. As the detective follows the trail, an organized front tries to buy Mannix off with a trip to Hong Kong on a supposed case. It turns out that the target of all this is a judge, whose daughter is in love with Joey. The syndicate wants to pressure the judge to move the site of a trial for an ...
Mannix has taken up a new hobby, amateur auto racing. While participating in a race, another racer is killed when his car seems to lose control and goes over an embankment. The widow of the dead racer contacts Mannix, wanting him to investigate, believing the death was a homicide. As Mannix proceeds, it's clear federal authorities have much more interest in what seems like a routine case.
A recently paroled ex-con is killed by a hit-and-run driver. The man had a matchbook with Mannix's phone number in it. Mannix tries to find out why the ex-con was killed. As his investigation, proceeds, Mannix discovers a plot -- and the detective may be its next victim.
An author, preparing a book about a well-publicized murder case in a small California city, is killed when his yacht blows up. The author's publisher hires Mannix to find the book's last chapter, which is said to solve the murder case. Mannix encounters a hostile police chief who wants to chase him off and an oil-company executive wanting to buy him off. Mannix refuses the bribe and endures a beating by the corrupt police chief but remains committed to finding the missing chapter.
Mannix is hired by successful heart surgeon Cameron McKenzie, whose young son was apparently kidnapped by someone who looked exactly like the doctor, driving a car that also looked exactly like the doctor's car. Mannix agrees to look into the kidnapping if the police will be notified once Mannix runs into a dead end. But then Dr. McKenzie confesses something he has held back: the kidnappers don't want a ransom -- they want McKenzie to let one of his patients die in exchange for the boy's life.
Mannix is hired by a secretive multi-millionaire to find his ex-wife. At least that's what he has been told when he takes the job. The ex-wife, a prominent singer, supposedly committed suicide but has been seen since her supposed death. As Mannix pursues the trail, it becomes clear he hasn't been given the entire story. The lives of Mannix and the ex-wife may soon come to an end unless the detective solves the mystery.
Mannix seeks to help a man released from prison after seven years. The detective helped send him to prison. This occurred when Mannix was on his first case and, as he remarks, "I was green" then. After the man's release, people start dying at his former employer. Mannix must probe two possibilities: whether the man was framed seven years or ago or whether he is seeking revenge now.
A young man named Clifton Ross (Mart Hulswit), the son of an aircraft magnate (David Brian), awakens after a night of drinking to find a bandage on his hand, blood on his shirt, and fragmentary memories of a fight with his girlfriend Doreen (Janaire). Ross learns that Doreen never came home the night before, and fears that his memories suggest that their evening together ended violently. Ross decides to hire Mannix to reconstruct the previous 24 hours of his life.
Mannix is traveling to Santa Barbara by helicopter when he sees a woman apparently being strangled on a penthouse terrace. When Mannix and the police investigate, however, they are assured by the occupants of the penthouse apartment that nothing has happened. Mannix refuses to accept this and launches his own investigation.
Mannix is brought to a small town in New Mexico on a ruse, and then subpoenaed to testify as an expert witness for the prosecution in a murder trial. After his testimony, the woman representing the defendant announces she wants to resign as defense counsel. Mannix decides that instead of returning to Los Angeles, he'll remain to aid the defense, encouraging the defendant's attorney to stick with the case while he tries to dig up new information that could free her client.
A jeweler whose shop is located near Mannix' detective agency is murdered, and in the crowd outside the murder scene, Mannix runs into Bill Chase, a buddy from his days in the Korean War. Chase tells Mannix he's in trouble and asks Mannix to visit the small mountain town where he serves as a fire ranger so he can tell Mannix about his situation. Within a short time of his arrival in the town, however, Mannix finds a deepening mystery, as he's shot at, injured falling down a hill, and learns that the woman who claims to be Chase's wife is a completely different woman.
A woman enters an apartment, is attacked and then thrown over a balcony to her death. The police conclude it is suicide, thanks in part to a phony suicide note. Friends of the woman's family hire Mannix to prove it's really a murder case so the woman can be buried in accordance with her faith. Despite his own doubts, Mannix becomes convinced it is a murder case. Yet the woman's father doesn't want the detective to pursue the case and then his clients abruptly terminate his services. Mannix, however, is determined to pursue the case.
A tennis pro tries to blackmail a candidate for governor, and is found dead in a remote area. His wife hires Mannix to investigate the man's death. Mannix travels to the state where the man died, and becomes embroiled in the political back-and-forth involving the candidate who was the target of the blackmail and his staff, as well as the activities of the candidate's opponents -- while also dealing with an oily woman who owns a chain of newspapers.
Mannix narrowly avoids being shot by a businessman who appears to be a solid citizen. The attacker claims this is due to dreams he is having based on his Korean War experiences. The businessman later freaks out when police approach his house. Mannix has begun to talk him down when the businessman is shot from outside. But the police didn't fire. Mannix continues his investigation and a student at UCLA, the daughter of a company the businessman knew in Korea, is the detective's main lead to finding the truth.
A young woman's body washes ashore as the episode opens, and Mannix later recognizes her as the former consort of a slippery attorney who once had Mannix' private investigator license suspended. Mannix suspects the attorney of having killed the woman, of committing another murder, and of staging the attempted suicide of someone who confesses to committing the two other two deaths, even though there is scant evidence to support his theories.
Peggy has been dating a black musician named Gabe Johnson. While they are at a jazz club, he and a man in the audience both recognize one another, and Gabe flees, without Peggy and without his prized cornet. Peggy turns to Joe Mannix and asks him to investigate Gabe's disappearance. Mannix learns that Gabe's real name is Gabe Dillon, and that the man in the club who recognized him (and whom Gabe recognized) was the police chief from the southern town where Gabe escaped while serving a ten-year prison term for burglary, attempted murder, and hit and run. Mannix ...
Mannix gets an urgent call from the police. Lt. Art Malcolm, Mannix's friend who also served with the detective during the Korean War, is being held hostage in an abandoned building. The police are unable to enter the structure, which is filled with explosive booby traps. The man behind Malcom's abduction served in the same outfit as Mannix and Malcom. The man was left behind when a group of G.I.'s escaped from a Korean prison camp. He has been revenging himself on the escapees and now only Mannix and Malcom are left alive.
Roger Bard, an Englishman who rents an office in the same complex as Joe Mannix, comes to work one day where he is first confronted by a man named Rhodes, whom he locks in a closet. Bard realizes that his office is being watched by three other men, whom he flees by escaping out a back window. Bard briefly climbs into the window in Mannix' office, where he gives Mannix his keys and asks Mannix to free Rhodes, before driving off with the three men in pursuit. Mannix discovers that Bard's office is an elaborate front, with no files or other paperwork of any kind. Then a ...
Mannix is hired to find Donald Jordan, a missing compulsive gambler. Mannix gets differing stories from Jordan's sister, wife and business partner. Then, he finds Jordan, who claims not to be in trouble. However, Jordan is being pursued by loan sharks. The detective not only seeks to establish the truth but also confronts those closest to Jordan, who have been enabling the gambling addict.
Mannix is hired to find a shipment of morphine -- "Miss Emma" -- stolen from a pharmaceutical firm. Peggy takes on a more active role than usual in trying to solve the morphine theft. Peggy also finds herself strongly attracted to Floyd Brown, a handsome black man who unsuccessfully tried to stop the morphine thieves, getting himself shot in the process.
Diana Walker, the daughter of a newspaper tycoon and Mannix' old flame, comes back into Mannix' life after a four-year absence. She is in a fragile mental state after believing that she killed a hoodlum named Johnny Malina, with whom she was also once involved, in a night-time road accident. Diana's father, sensing that she's terribly upset about something, asks Mannix to contact her once again, hoping that she will confide in Mannix about whatever is disturbing her.
Mannix is called in the middle of the night by an acquaintance, Pete Neal, and offered $1,000 to protect a man named Frank Devereau just until the following morning. Devereau is carrying $250,000, but he and Neal insist that the money is not stolen. Suddenly a car swerves by, shots ring out, Neal is killed, and the car disappears with both the money and Neal's body. Then Devereau runs off, too, leaving Mannix to report the shooting and disappearance of the money to the police with no other witnesses, no physical evidence, and no explanation where Devereau got such a ...
Peter Martin, the son of a respected doctor who often ministered to the less fortunate, is found at the bottom of the stairs in his home with his neck broken. His sister does not believe the medical examiner's conclusion that his death was accidental, and hires Mannix to find out if he was murdered, and if so, by whom. A clue left by a young boy whom Mannix observes spying on the Martin home leads Mannix to a Chicano neighborhood, where he discovers further evidence about Martin's death, but also uncovers resentments and accusations toward Martin by some residents of ...