A research scientist hires old friend Cannon when her husband begins to display erratic behavior after joining a top-secret Army project.
An angry father is determined to prove his son's death in a plunge from the cliffs of Acapulco was not a suicide; guest Frank Aletter.
A revenge-seeking father sets out after his slain daughter's pro football quarterback boyfriend despite the solidity of the man's alibi.
Cannon is hired by a racketeer (Robert Loggia) to capture the hired killer responsible for an attempt on the life of the gangster's wife.
Cannon investigates possible extraterrestrial involvement in the death of an internationally known space scientist; guest Eric Braeden.
A multimillionaire hires Cannon to avoid police involvement in the possibly fraudulent kidnapping of his grandson; guest Ralph Bellamy.
Cannon's military past in Korea returns to haunt him when he becomes the target of a South Korean officer's revenge; guest Gary Merrill.
The disappearance of an accountant coincides with a huge fraud investigation set to begin against his employer, a land-development firm.
Despite hints of a frame-up, a crusading newspaper editor is arrested after being found unconscious with a murdered girl in a hotel room.
A boy is initially disbelieved when he claims two men dressed as Arabs shot at him while they wheeled a patient into a makeshift hospital.
A former film actress (Joan Fontaine) hires Cannon to find her son, who disappeared just after returning from three years of traveling.
The son (Carl Franklin) of a slain black political leader hires Cannon to look into the possibility of a conspiracy; guest Herb Edelman.
A retired general's (Morgan Woodward) son (Dean Stockwell) becomes a hero to his father after being accused of killing a terrorist leader.
A policewoman comes to Cannon for help when her superiors won't let her hunt the men who assaulted her; guests James Olson, Tina Louise.
An heiress's boyfriend receives a death threat from the Chinese underworld in the form of a melting snowman with a hatchet in its head.
A petroleum company's vice-president, on the verge of being fired after being accused of misappropriation of funds, asks Cannon for help.
As a favor, Cannon agrees to travel to Mexico to get the body of his former police mentor's son; guests Stuart Whitman, Chris Robinson.
Terrorists give Cannon poison that will kill in 72 hours without an antidote, which they will exchange for a defector.
Cannon and his old police partner (Leslie Nielsen) are asked by their ex-superior to reopen the probe of a corrupt officer thought dead.
A drugged, battered girl insists her friend (Donna Mills), a singer, is being held prisoner in the Hollywood hills; guest Joel Fabiani.
A reopened murder case involves a former Green Beret and a convict who surprisingly rejects parole; guests Robert Foxworth, Dennis Patrick.
Cannon looks into charges against a physician (David Birney) in the death of a woman he was treating who was in an apparent diabetic coma.
As a favor, Cannon investigates the case of a liquor deliveryman charged with murder; guests Lee Meriwether, Buddy Ebsen, Sharon Acker.
Cannon hears the confession of a hit man who admits to killing the detective's wife and baby son 14 years before; guest Elizabeth Allen.
Cannon uncovers a crime during his search for a teenage runaway; guests Dana Wynter, James Wainwright, Abe Vigoda, Priscilla Pointer.
Cannon has a 24-hour deadline to rescue a wealthy industrialist's daughter after she is taken by a terrorist group; guest Charles Cioffi.
An ex-convict (Clu Gulager) attempts suicide to force Cannon to search for the fake CIA agent who sent him to jail; guest Monte Markham.
A disenchanted wife flees to a sanitarium she once inhabited after seeing her lover commit a murder; guests Barbara Rush, Barbara Luna.
A Midwestern mayor calls in Cannon to clean up police corruption in his community that has resulted in a string of warehouse burglaries.
Cannon suspects he has a double after two nearly successful attempts on his life follow a strange woman's greeting to him at the airport.
A former convict boards an Atlanta airliner for a reunion with his daughter but is missing when the plane lands; guest Bradford Dillman.
Cannon encounters corruption when he investigates the attempted assassination of a state assemblyman; guests Michael Tolan, Brooke Bundy.
Cannon is framed when the supposed pursuer of the girl he was hired to protect is found murdered; guests Ralph Meeker, Kathleen Cody.
A lawyer (Gary Lockwood) returns to the scene of his college football triumphs to escape a crime mob pursuing him; guest Patty McCormack.
A tape recording detailing the murder of a girl reported missing brings Cannon to a rural town to solve the crime; guest Tom Skerritt.
Cannon becomes the target of a setup when he fakes the murder of a mobster to allow the man to testify against the mob as part of a deal.
Cannon goes under cover as a hired killer to uncover the dark secret behind the blackmail of a former Army captain; guest Peter Haskell.
A chess champion and financial wizard suddenly breaks off his engagement, leading his puzzled fiancee to ask Cannon to find the reason.
Cannon finds himself involved in an assassination attempt and the manhunt for an alleged World War II criminal; guest Leslie Nielsen.
A falsely accused suspect faces injury at the hands of a mob unless a rapist/murderer's mother reveals vital evidence; guest Ruth Roman.
Cannon feels victimized when he discovers the true identity of the insurance man who hired him to look into a girl's auto-accident death.
An ex-police officer (Dane Clark) intends to avenge his brother who died while doing a favor for Cannon; guests Kay Lenz, Greg Mullavey.
Cannon becomes involved in a terrorist's vendetta through his friendship with the intended victim, an ex-colleague; guest Robert Loggia.
A domineering tycoon whose daughter has been missing for a long time tries to force Cannon to search for the girl; guest Kevin McCarthy.
The woman Cannon was hired to guard eludes him at the airport, only to turn up later robbed and slain; guests Steve Forrest, David Soul.
An unofficial probe conducted by Cannon's friend (Ford Rainey), a retired police officer, makes both him and Cannon targets for hit men.
To save a Catholic bishop (Richard Kiley), Cannon must pose as a hired assassin and infiltrate a crime mob; guest Christopher Connelly.
A retired call girl (Stefanie Powers) resists cooperating when Cannon asks her to be the lure in a police plan to trap her former boss.
An escaped mental patient bent on vengeance stalks Cannon during the investigator's vacation at a mountain lake; guest Cindy Williams.
An English heiress (Dana Wynter) suspects the supposedly suicidal death of her father on a Caribbean island was in reality a homicide.
A naive schoolteacher hires Cannon to investigate the murder of her love interest, a smooth-talking dance teacher at a lonely-hearts club.
Cannon moves among evangelists and carnival performers while probing the disappearance of a faith healer's protege; guest Peter Strauss.
The widow of a big-game hunter believes her husband was murdered, despite evidence suggesting he was mauled to death by an ailing lion.
A flamboyant attorney (Peter Haskell) defends a doctor (Perry King) charged in the death of a financier during an apparent jail escape.
A shy heiress hires Cannon to stop attacks of vandalism she claims are the handiwork of her long-missing sister; guest Pamela Franklin.
On a mission to deliver ransom money, Cannon falls prey to opportunists while wandering in the desert with amnesia; guest Joan Van Ark.
Cannon becomes the target of a sniper when a mercenary (Jack Cassidy) hires the detective for a murder investigation; guest Hal Williams.
A boxing contender's (Nick Nolte) fiancee asks Cannon's help when the fighter threatens to leave the country just before a major bout.
Cannon finds a clue to a bizarre harassment case in the involvement of a pilot (Robert Goulet) in a $1 million hijacking years before.
Cannon contacts the legal counsel (Leslie Nielsen) for an American Indian organization when he tries to clear an Indian of murder charges.
A socialite (Dina Merrill) is astonished to discover that her missing fiance is actually a married man being sought by his Swiss wife.
A judge's (Simon Scott) daughter (Kelly Miles) disappears while her father is presiding over a case involving a major syndicate kingpin.
Cannon's longtime friend (Jason Evers), a police detective, is suspended after the escape of the top suspect in a counterfeit-stock ring.
Cannon enters the circle of admirers around a lovely model when he tries to clear the man charged with her murder; guest Dabney Coleman.
Cannon's prime suspect in a $50,000 payroll burglary at an electronics plant turns out to have been in jail when the crime was committed.
Cannon agrees to search for an escaped convict who may have been framed on a murder charge; guests Michael Tolan, Don Stroud, John Larch.
Cannon investigates the unexplained disappearance of an airplane carrying $3 million in securities; guests John Vernon, David Hedison.
An innocent publicist (Anne Francis) finds herself charged with a producer's murder when she becomes involved in a complicated conspiracy.
Cannon is accused in the slaying of a mobster's girlfriend who contacted him in hope of getting government immunity for her lover.
Killer dogs slay two survivors of an Army unit whose commanding lieutenant became paralyzed in a deliberate attack; guest Geoffrey Deuel.
A lawyer (Martin Sheen) presents Cannon with a will provision requiring the detective to look into the death of the lawyer's late client.
Cannon faces a small cattle town's hostility when he tries to clear a friend of two homicide charges; guest Anne Baxter.
A wealthy arts patron (Beverly Garland) hires Cannon to find her long-missing stepson; guests John Anderson, Lynne Marta, Glynn Turman.
A news reporter (Marlyn Mason) asks old friend Cannon to help her when she faces a contempt charge for refusing to reveal a news source.
An admitted mass murderer (Anthony Zerbe) hires Cannon and tells the investigator to prevent him from killing again; guest Dana Wynter.
A rural newspaper editor (Barry Nelson) hires Cannon to find evidence linking a powerful local community leader to a series of murders.
An importer's ex-wife (Geraldine Brooks) hires Cannon when her son is reportedly jailed on a drug charge in Turkey; guest Harold Gould.
Cannon attempts to locate both a missing lawyer and the killer of a police officer; guests John Larch, Christine Belford, Stewart Moss.
Cannon tries to prevent the violent revenge sought by a high-school teacher whose daughter died at a jet-set party; guest Jason Evers.
A photographer (Susan Oliver) finds Cannon hesitant to search for her missing boyfriend after the detective learns his quarry's identity.
A suspect (Sondra Locke) is missing in Cannon's investigation of the death of a famed marine biologist; guests David Soul, Tim O'Connor.
A would-be actress (Arlene Golonka) becomes the pawn in a plot to take over a real-estate empire; guests David Hedison, Barbara Babcock.
Unknown assailants plague an amnesia victim (John Vernon) who appears to know an important secret; guests Fritz Weaver, Greg Mullavey.
Cannon pursues a mob kingpin threatening the life of a gambler's wife; guests John Marley, Tom Skerritt, (Paul) Michael Glaser.
Cannon's old friend (Andrew Duggan), a boat builder, finds himself charged in his son's hunting-accident death; guest Billy Green Bush.
A former policewoman hires Cannon when her husband becomes the victim of blackmailers; guests William Daniels, Linden Chiles, Wesley Lau.
Cannon looks into the disappearance of a real-estate tycoon's body after the man's plunge from a precipice overlooking a development site.
Cannon leads the hunt for a missing rancher who has been taken hostage by a hostile narcotics smuggler; guests Clu Gulager, Julie Adams.
Cannon accidentally uncovers a major-league hijacking operation; guests George Maharis, Stephanie Powers, Robert Mandan, Max Gail.
Cannon tries to clear a black physician who has been framed in a drug-theft case; guests James A. Watson Jr., Dana Elcar, Ned Romero.
Cannon aids a sheep rancher charged in the death of an illegal Mexican immigrant caught in a coyote trap.
A rival private investigator pressures Cannon in the matter of a drinking-establishment fire.
Cannon is hired to protect a lawyer (Jessica Walter) whose clients are unpopular with the public; guests Robert Webber, Clete Roberts.
Cannon's search for a missing husband reveals plans for an upcoming, daring robbery; guests Irene Tsu, Lloyd Bochner, Micky Dolenz.
Deaths resulting from a ski-lift tragedy bring Cannon to Colorado to investigate; guests Leslie Charleson, Richard Hatch, Ken Scott.
A man accused of murdering his wife is also a close friend of Cannon's; guests Michael Tolan, Marj Dusay, Severn Darden, Larry Linville.
A young convict falls prey to a prison mastermind who is in charge of a vast gambling empire operating behind bars; guest Lin McCarthy.
A wealthy manufacturer and gun collector whose younger brother has suddenly vanished hires Cannon to investigate; guest Bradford Dillman.
A man accused of setting the fire that killed his estranged wife comes to Cannon for help in proving his innocence; guest Anthony Zerbe.
A mercenary group comes up with a plan to overthrow the government of a small African country; guests Martin Sheen, Gerald S. O'Loughlin.
Frightened parents call in Cannon when their teenage daughter falls under the mystical spell of a cult leader; guest John Rubinstein.
The life of a safecracker trying to stay within the law is threatened if he fails to cooperate in a $1 million theft; guest Keenan Wynn.
Cannon discovers an impostor posing as the son of a winemaker whose life has been threatened; guests Theodore Bikel, Katherine Justice.
A harassment campaign is directed at a doctor (Vera Miles) engaged in a medical research project at a state prison; guest Arthur Franz.
Cannon pursues three hoodlums who stole valuable artifacts from a church in Mexico; guests Tab Hunter, Alejandro Rey, Victoria Racimo.
A disabled ex-motorcycle officer seeks revenge on the man he holds responsible for his injuries; guests Martin Sheen, Daniel J. Travanti.
A thief dupes Cannon into providing him with a plan to change his identity and escape the country; guests Cesare Danova, Barbara Luna.
A disgruntled accountant plans to protest the production of deadly nerve gas by stealing a canister of the substance; guest Fritz Weaver.
Cannon's simple assignment as bodyguard to a broker's daughter and grandchildren suddenly turns complex; guests Ed Nelson, Leif Garrett.
A missing bicycle provides a vital clue in Cannon's investigation of a salesgirl's mysterious death; guests Richard Anderson, Dack Rambo.
Cannon's work in a missing-persons investigation is hampered by a firm's attorney; guests Arthur O'Connell, Linda Marsh, Roy Scheider.
A frightened woman hires Cannon to find her missing brother, whom she fears is a homicide victim; guests R.G. Armstrong, Harold Gould.
A police detective who has been framed on a murder charge asks Cannon for help; guests Brooke Bundy, James Wainwright, Barnard Hughes.
The death of a private-investigator friend during a missing-persons case leads Cannon to join the probe; guests Kim Hunter, Andrew Prine.
The trail of suspects in an armored-car robbery leads Cannon to a hamlet where he receives an unfriendly greeting; guest Andrew Duggan.
Cannon is called in when a gubernatorial candidate wants to avoid police involvement in rescuing his kidnapped son; guest Tim O'Connor.
An insurance company hires Cannon to investigate the plane-crash death of a country-and-western singer; guests Clu Gulager, Joan Van Ark.
A trucking firm hires Cannon to find those responsible for a series of hijackings; guests Patricia Smith, Wayne Rogers, Charles Cioffi.
The death of a secretary prompts her employer, a middle-aged banker, to hire Cannon to investigate; guests William Windom, Sorrell Booke.
An insurance firm hires Cannon to find the thief who robbed a rodeo of $100,000; guests Sharon Acker, Tom Skerritt, Vincent Van Patten.
Private detective Frank Cannon investigates the murder of his ex-girlfriend's husband and gets entangled in small-town corruption.
Private detective Frank Cannon investigates the murder of his ex-girlfriend's husband and gets entangled in small-town corruption.