In the pilot episode, Magnum accidentally uncovers a drug operation in the islands when picking up an old Navy friend of his at the airport and helps his friend's sister uncover the truth about a conspiracy involving the NIA and Southeast-Asian drug dealers. Magnum makes a casual reference to predecessor series Hawaii Five-O after his pursuers drive over a cliffside. When his friend winds up dead, Magnum must find his killers and uncover a smuggling ring that leads him to people from his past during the Vietnam War.

Magnum helps protect a dog from being kidnapped by a gangster and his two sons. Guest stars: Michael V. Gazzo and Kathleen Nolan

A Supreme Court nominee hires Magnum to locate his ex-prostitute wife who has been missing since the Pearl Harbor Attacks forty years earlier. Guest stars: Miguel Ferrer, José Ferrer, Anne Lockhart and June Lockhart

When T.C. is arrested by the United States Coast Guard for smuggling a deserter of the United States Marine Corps into the islands, Magnum and Rick must uncover their best friend's real motives, but also discover a plot made by drug smugglers. This episode was the immediate answer to the episode number 8, "The Ugliest Dog in Hawaii".

With just a ten year old postcard as a clue, Magnum is hired by a Kansan woman, Cindy Lewellyn (Anne Bloom), to find her missing father Floyd (Noah Beery) who's a small-time con man on the run.

Magnum is hired by a blind friend to negotiate with a blackmailer and discovers a plot to murder his friend.

Because of a threat to his life, Robin Masters (voiced by Orson Welles) hires Joy "Digger" Doyle (Erin Gray) to check the security at the estate. She meets Magnum, and, pretending to be a big fan of Robin's, manages to penetrate the estate. The security agency locks down Robin's Nest and enlists the help of Magnum, Rick and TC to prevent a hit on Robin. Higgins is kidnapped in the process, but Magnum and Digger manage to save him. Magnum later discovers that the plot to kill Robin emanates from within the security agency.

After her archaeologist father's boat is found deserted at sea in the Nihoa Channel, a marine biology student hires Magnum to find out what happened to him. The local natives warn Magnum to stay away from the "cursed" channel, but he's determined to find out what happened to the missing man.

A year after escaping from Moscow in a MiG 23 fighter jet, a Soviet defector hires Magnum to help his girlfriend defect from an Olympic track team visiting Hawaii. She is under close watch of undercover KGB agents, and Magnum, T.C. and Rick, with assistance from Higgins, must carry out their plan with military precision to free her.

Magnum, T.C., and an ex-army buddy named Nuzo (James Whitmore Jr.) try to track down Ivan (Bo Svenson), a Soviet KGB officer who held them captive during the Vietnam War. Nuzo claims Ivan has been stalking him, and that Ivan is after all of them. Meanwhile, Lieutenant "Mac" MacReynolds (Jeff MacKay), claiming that he has resigned from the Navy, starts hanging around Magnum. In reality, Mac hasn't resigned but is working under Buck Green's orders to keep tabs on Magnum because Magnum's name has surfaced in connection with a Soviet Intel operation set to take place in Hawaii. After a night out at a bar, Mac is killed by a car bomb when he gets into Magnum's Ferrari ahead of Magnum. Magnum vows revenge. Magnum discovers that Nuzo, who is actually Ivan's operative, has hypnotized T.C. and convinced him to kill a visiting Japanese dignitary. Magnum stops T.C. in time, but due to diplomatic immunity Ivan is set free, his next target perhaps being the president. With Rick's help, Magnum captures Ivan, who admits to killing Mac (in an attempt to kill Magnum), and taunts Magnum and tells him that he can't do anything to stop him. At the end of the episode, Magnum asks Ivan, "Did you see the sunrise?", echoing a wish Mac had expressed with his last words. Ivan replies "yes", and Magnum turns towards Ivan, raises his gun, and fires.

Magnum is assisted by the Simon brothers (Gerald McRaney and Jameson Parker) in finding a stolen Hawaiian artifact that's supposedly cursed. Guest star: Morgan Fairchild

This episode begins a crossover event that concludes on Simon & Simon season 2 episode 1.

Magnum dreams he's in 1936—populated with versions of his friends—where he's working for a young woman whose father, a union leader, has been accused of the murder of a construction magnate.

When a feisty cocktail waitress, Bridget Archer (Kathleen Lloyd) is denied permission to scatter her late father's ashes at the USS Arizona Memorial in Pearl Harbor due to a court martial ruling that he was AWOL, she turns to Magnum to prove her father was indeed present during the infamous Japanese raid.

Magnum investigates the crash of a small plane in the Estate's tidal pool and discovers it wasn't an accident and that the pilot named Sam Houston Hunter (William Lucking), he vaguely recognizes, helped save him in the Vietnam War.

St. Louis gumshoe Luther H. Gillis returns to Hawaii, accompanied by his secretary Blanche Rafferty (Sheree North), to attend the annual Private Investigators convention, where Luther has been informed he will receive an award. But while Luther and Magnum attend the convention, Higgins and Blanche are kidnapped from the Estate, and the two P.I.'s find themselves having to join forces once again.

A young woman named Diane Dupres (Sharon Stone) claims she is being stalked by her twin sister, Deirdre, and hires Magnum to investigate. Magnum breaks his number one rule and becomes romantically involved with a female client. Diane begins to show signs of paranoid delusions when she calls Thomas in a panic claiming to have shot a man at her residence although Magnum and Higgins can find no obvious signs of an attack. Magnum stays at her residence out of concern for her well being, and the episode ends with Magnum taking a shower and Diane (or is it Deirdre?) stepping in to join him.

A psychic named Laura Bennett (Samantha Eggar) hires Magnum to save her from the future she's seen for herself - being murdered. Meanwhile, Magnum also finds danger in trying to get paid by Archie (Kenneth Mars), a sneaky car salesman client. Higgins organizes a benefit variety show.

After thirteen years away, Magnum returns to his hometown of Tidewater, Virginia to attend the funeral of his grandfather, Everett, and reopens a long-running family feud when he suspects his stepfather Frank Peterson (David Huddleston) of stealing and selling a missing family heirloom — a letter from Abraham Lincoln.

Another of Higgins' half-brothers arrives (John Hillerman in a dual role), this one the last in the royal line of Costa Del Rosa and who ends up a suspect in a plot to assassinate the country's president at a chess tournament.

While the others are away, Magnum begins the hated task of filling out his tax forms for an audit but is interrupted by a phone call from a serial killer with a nursery rhyme for him. The man then hints that he knew about Philippe (from "Don't Eat the Snow in Hawaii"). When a prostitute and former client of Magnum's is found dead, Magnum ties together the murder with the nursery rhyme. After several more phone calls and another murder, Magnum confronts and kills the murderer, who turns out to be Milton Collins (Kenneth Tigar), a former client. Magnum concludes that Collins "died with all the secrets", as Magnum never found out how Collins knew about Philippe.

Jessica Fletcher (Angela Lansbury), on vacation in Hawaii, offers to help Magnum, who has been accused of killing a hitman with an unknown target, and continues in his corner when another murder occurs. Jessica Walter and Dorothy Loudon also guest star.

During a hike in the mountains to clear his head, Magnum becomes trapped under the wreckage of an old fighter plane and must stay alive, while also thinking about a case he was recently fired from and reminiscing about his life in general.

Magnum is hired by a retired NYPD Det. Sgt. named Michael Doheny (Frank Sinatra, in his last credited screen acting performance) to find the killers in an unsolved Bronx homicide, who are now living in Honolulu. It turns out that the little girl that was raped and murdered by the men Doheny was after, was in fact Doheny's granddaughter, Laura. Magnum helps the detective find the killers and bring them to justice, with the help of Rick and Lt. Nolan Paige (Joe Santos).

In what was originally meant to be the final episode of the series, Magnum is critically wounded in a dockside warehouse firefight and ends up in a coma. He "wakes up" in Limbo with Mac but refuses to believe that he is dead, insisting that he is only dreaming, even though no one but Mac can hear or see him. Magnum finally accepts that he is dead, and says his goodbyes.

Still healing from his near-death ordeal and experiencing Mac's ghost, Magnum is surprised when Higgins hands over his estate duties to be able to take some time off. In a bizarre twist, Higgins starts living the fast and loose life, wears loud Hawaiian shirts and becomes irresponsible, while Thomas assumes Higgins' stuffy personality and ways, going so far as to wear a suit. Curious about Higgins's sudden change in personality, Thomas investigates and discovers that Higgins is seeing a woman named Rosita Esteverdes (Julia Migenes) on the sly, and becomes concerned that she is taking Higgins for a ride, while the woman is being stalked by Miguel Torres (Gregory Sierra), a mysterious man.

Robin Masters is sued by a man who tripped at a recent party on the estate. As Magnum begins to investigate the man, Joe Hatten (Kenneth McMillan), a loud-mouthed businessman who seems to be a professional at making false claims, Hatten unexpectedly pays him to take Rita Parker (Janis Ward), his perky fiancee, along on the case with him.

When Quang Ki (Richard Narita), who attempted to kill him and Michelle, is set free on a technicality, Magnum tries to gain information about the whereabouts of Michelle and Lily from Buck, who refuses to help. When Magnum receives a videotape of the murder of Michelle and Lily, he vows revenge and arms himself with a sniper rifle and commando gear. But when he learns that Ki will be exchanged for an American P.O.W. released from Vietnam after more than twenty years in captivity, Magnum reluctantly forgoes killing Ki for the sake of preserving good relations between the U.S. and Vietnam in order to free more P.O.W.s.