When Thomas's childhood friend and Naval comrade Dan Cook turns up dead, Thomas is adamant that the official cause of death, a burst bag of smuggled cocaine, is bogus, and enlists the aid of Dan's sister Alice in taking on the Navy to uncover the true nature of the top-secret assignment Dan was working on before his death.

Conclusion of the feature-length / two-part Pilot. Magnum and Alice continue in their quest to find out the truth behind Lt. Dan Cook's death, and find themselves uncovering a case of gold smuggling, and a criminal mastermind whom Magnum and Dan once knew in Vietnam. But in trying to find out what really did happen to his deceased friend, Magnum puts his own life on the line as someone tries to stop him from investigating, using any means necessary...

A new singer at the King Kamehameha Club who claims to have E.S.P. hires Magnum to find her childhood friend-come-fiancée Eric, a Marine who has been listed as Missing In Action since 1972, whom now she has started getting psychic visions of. As he investigates, Thomas discovers that Eric was a member of the top-secret 'Delta Section', and is refusing to come in from the cold until he exposes the division's activities to the press – but is being pursued by a Delta operative who is determined to bring Eric in and keep him quiet, at any cost...

T.C. makes a late-night flight to land on a tanker, but on the journey back he is cornered arrested by the Coast Guard for transporting drugs. Magnum and Rick are certain of their friend's innocence, but are bemused when he intends to accept the charges and refuses their help. Magnum investigates, to find that T.C. trip to the tanker was to collect and bring home a man who once saved T.C.'s life in Vietnam, a deserter who is now a supposedly reformed drug addict, who was calling in an old debt to be flown back in to U.S. territory...

Thomas is hired by Barbara Terranova, a financially broke woman who can only afford his services for one day, to find her missing fiancé Roger. But the case has several tangles in store when Magnum finds there are others searching for Roger too; And matters are complicated even further when T.C., desperate for some much-needed publicity for Island Hoppers, collars him into competing in the upcoming swim-run-bike Ironman triathlon. Fitness trainer Barbara trains him for the event in exchange for his extended help in locating her fiancé...

After her archaeologist father's boat is found deserted at sea in the Nehoa Channel, a young marine biologist student hires Magnum to find out what happened to him. Ancient superstitions say that the channel is ""cursed"", and local natives warn Magnum to stay away, but he is determined to get to the bottom of what happened to the missing man, and so, with aid of Rick's yaught, they go hunting for both sunken treasure, and whoever was behind the girl's father's disappearance...

While working on a routine divorce case, Thomas catches a brief glimpse of a woman on a passing boat that he is certain is Michelle, the girl he married during the Vietnam war seven years ago, and whom he previously believed to have been killed shortly afterwards in a bombing raid. All he has of the brisk sighting is some blurred photos he managed to take, and T.C. and Rick, whilst not completely convinced, help as he scours the local area looking for her. But there are several parties that intend to see that Thomas is unable to make contact with Michelle, and the search sees them stumbling into dangerous political territory.

In the conclusion of this feature-length / two-part story, Magnum's desperate search for Michelle faces being forced to a halt after he has been called up for active Navy duty and ordered to testify in Washington. Thomas suspects that is just a political smoke-screen to try and get him off Michelle's trail. Briefly re-united with Michelle, who is married to Vietnamese General Hue, who is involved in delicate negotiations regarding the returning remains of M.I.A.s and P.O.W.s from Vietnam. But Michelle is suspected of being a traitor agent and is in great danger...

As a favour to Robin Masters, Thomas finds himself acting as body-guard to a famous ballerina, part of a visiting troupe, after she has had several attempts made on her life. The dancer's stuboness sees sparks flying between the pair as Magnum tries to protect her - and T.C.'s previously undeclared love of ballet comes in useful, with him more than willing to help Thomas out on the case for once. Meanwhile, Rick accepts a job on Magnum's behalf, to investigate a woman's husband, but Thomas becomes suspicious that the timing of the job is rather too coincidentally and comes to suspect that he's been hired for another reason; and the whole situation sees him uncovering a case of international intrigue...

Magnum is caught in the crossfire of international politics and terrorism when a determined news correspondent that himself, T.C. and Rick met in Vietnam, arrives in Honolulu, asking his help in tracking down a master-of-disguise international assassin who is targeting a visiting Prime Minister of a small island republic. But as they try to locate the killer before the assassination attempt is made, Thomas begins to question the exact motives behind the reporter's extreme determination to get the story...

While working for a large corporation to investigate a case of computer espionage, Magnum is hired by one of the company's presidents to check out his wife, whom he suspects is having an affair. But Thomas finds himself in a compromising position of split loyalties when it turns out that the man that the woman is seeing is none other than Rick. Meanwhile, Higgins is expecting a visit from his once fiancée, and enlists Thomas' help in getting in shape before her arrival...

First part of what was originally shown as a feature-length story. Nuzo, an old war comrade of T.C. and Magnum's, suddenly arrives in Hawaii, and finds T.C. to warn him that Colonel Ivan, a sadistic Russian agent who once held them captive and tortured them in a P.O.W. camp in Vietnam, is after them. At first, T.C. puts his old buddy's fears down to delayed stress, but it gradually begins to seem that there might be some truth in his claims. Meanwhile, Lt. MacReynolds resigns from the Navy, and Magnum lets him stay with him for a few days, but a fatal accident meant for Thomas - as yet unaware of Nuzo's warnings - adds ground to the fears that maybe Ivan is on the trail after all...

Conclusion of this feature-length / two-part story. As Magnum, T.C. and Nuzo plan to get to Ivan before he kills them, the Navy – inparticular Colonel Greene and Admiral Hawkes – have their own concerns in the situation and questions regarding Mac's death. But things are not as previously thought about Nuzo, and not only is T.C.'s life in great danger, but many other people's too as a result, in part of an assassination plot of a Japanese prince...

Diane's suicide triggers memories of others that Magnum has loved who have been killed, sending him into a spiral of depression, with him fast becoming a drunken wreck. While driving through town, he catches a glimpse of a man in who looks exactly like his late friend Mac MacReynolds. Higgins, Rick and T.C. are concerned about the effect of Diane's suicide on Magnum, but Thomas is adamant that he isn't going around the bend and intends to prove to his friends and to himself that he's not going insane. But if Mac is dead, just who did Magnum see?

At request of Robin Masters, Thomas begrudgingly is to provide protection for a political candidate whom he has reason to dislike. He is also waiting for a female client, but in her place arrives a young Vietnamese boy, Tran Quoc Jones, who wants to hire Magnum to find his long lost father, a pilot in the Vietnam war. Tran cannot go to the authorities for help as he is an illegal immigrant and would face deportation, and as Thomas does his best to trace the boy's father, he and his friends, especially T.C., become attached to the boy. But Magnum learns that the woman who was originally to have hired him was found murdered - and the politician, the dead woman and the young Vietnamese boy all tie in to the same case...

Higgins is outraged when Thomas's game playing crashes the estate's security computer system, thereby jeopardizing the selection of the estate for an upcoming multi-million dollar jewelery design competition; Thomas enlists Mac's help in reprogramming the computer in exchange for bailing him out of jail after he's been arrested for possession of stolen goods; after challenging Krista, the insurance company's wily security investigator who learned her trade at the knee of her jewel thief father, to test the Estate's security system after Mac gets the system up and running again, Thomas discovers that Mac has greatly overstated his programming abilities and that Krista has greatly understated her father's retirement.

Mac's latest shady money-making scheme has landed him in trouble with the Japanese Yakuza, so he convinces Rick to buy a sailboat from him, complete with a crew of three Japanese women who barely speak a word of English. Rick is furious when Mac skips town just before the boat is impounded because Mac didn't own it in the first place, leaving Rick unable to repay Ice Pick the $20,000 he borrowed to buy the yacht, now that he can't make the money he planned by renting the boat out for charters. To get Rick's money back and keep the Yakuza and Ice Pick from doing him harm, Thomas sets out across the mainland to track down Mac.

1940s San Francisco: Private Investigator Thomas S. Magnum investigates the murder of newspaper tycoon William Maxfield. The case involves characters that strangely bear a strong resemblance to (modern day) Magnum, T.C., Higgins and Rick...

T.C. is giving Thomas helicopter flying lessons when he is shot. With T.C. hospitalised, Mac appears on the scene, ""volunteering"" his services to stand in running Island Hoppers. But it seems that the assailants were actually gunning for Magnum, after a week previously, somebody impersonated him when trying to blackmail a Mexican Mafia King. With Magnum marked as a dead man as a result of the mistaken identity, confusion and chaos reigns, and as per usual, Mac 'just happens' to be in the middle of it all...

Thomas is delivering key evidence at the courthouse when he is shot in the parking lot by a hitman. In a coma, Thomas needs to save Michelle from some killers, and meets up with the ghost of his former Naval buddy Mac. Then he bids each of his friends a personal goodbye, in case he doesn't make it.

Thomas lies hospitalized in a coma, caught between life and death, after being shot; as his friends and family attempt to pull him out of the limbo in which he is trapped, Thomas has an out-of-body experience in which he sees himself in heaven, guided by Mac; Thomas recovers physically from the gunshot wound in time, but finds it hard to face life again; although three of the criminals who almost killed him are already dead, one is still free.

Still healing from his near-death ordeal and experiencing Mac's ghost, Thomas 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 on the sly, and becomes concerned that she is taking Higgins for a ride.