A man and a woman hire Magnum and Higgins to find the woman’s brother, which turns out to be a ruse to find the guy and kill him, whereupon Higgins gets shot and is taken to the hospital.
As Magnum and Higgins are hired to retrieve a plane, they get shot at after taking off, forcing them to crash land, whereupon they discover that it’s being used by a drug ring, when they find a guy hiding on board, who claims to be a DEA informant.
Masked men take hostages in the building, where Higgins and Magnum meet with a federal immigration agent to get Higgins a green card, whereupon the duo intervenes.
As a mixed martial arts fighter goes missing, her father seeks Katsumoto’s help, and when he contacts Magnum and Higgins, they find out that the fighter has been kidnapped and forced to enter an illegal fight by Japanese mobsters.
Magnum and his friends take shelter in Rick’s bar during a hurricane, where they find out that two of the customers are actually armed thieves who’ve just killed two guards, assuming their identities.
When a wealthy man’s wife goes missing, he hires Magnum and Higgins to find her, whereupon her kidnappers demand a large ransom, only for the duo to discover that there’s something fishy about the whole matter.
When two guys from a neighborhood watch contact Magnum and Higgins to stake out their neighbor, whom they suspect is a murderer; the duo tries to get to the bottom of it, with shocking results.
Ethan asks Magnum and Higgins to find Paul, a patient of his with a punctured lung from a bullet who went missing. While TC helps a Marine friend with finding recruits, he comes across a guy enlisting for the wrong reasons.
The son of an ex-client of Magnum’s kidnaps Higgins in retaliation for his turning in his father who’s now in prison, demanding that Magnum breaks him out in exchange for Higgins’ life.
A woman hires Magnum to find her husband, an army ranger who came back home suffering from survivor’s guilt, before he does anything rash. While on vacation, Higgins and Ethan are approached by a hotel guest to help him find an engagement ring.
When an adulterous woman asks Magnum and Higgins to find the killers of her lover, the duo is unable to contact Det. Katsumoto; however, he gets involved, and they manage to crack the case.
When a veteran’s SUV is stolen with her dog in it, Magnum and Higgins set out to find both, whereupon they learn the story of the thief, who is a kidnapping victim himself.
Magnum and Higgins have to solve a case involving rare, costly truffles while taking care of a baby who’s been abandoned at the gates of Robin’s Nest.
A psychic hires the P.I.s, claiming that a man will murder his wife. Despite being skeptical, the duo investigates the case, only to find out that the psychic herself was murdered. When a bag full of stolen jewels is found with a card that has Kumu’s name on it, Katsumoto questions her about it.
When Magnum’s uncle comes to visit, he reveals a surprising family secret. Higgins comes clean to Ethan about her past. As TC believes he has witnessed a murder from his helicopter, he enlists Katsumoto’s help.
The P.I.s are hired by Chloe, who learns she’s being stalked as she finds a tracker planted in her car, leading the duo to unravel the case, which turns out to involve a Russian spy. Ethan forgives Higgins and asks her to join him on a trip to Kenya.