A decorated former Navy SEAL who, upon returning home from Afghanistan, repurposes his military skills to become a private investigator in Hawaii.

TC asks Magnum to take on a case to help acquit the father of one of his young football players, who is accused of murder.

An aging tycoon asks Magnum to find his lost love who he says just recently contacted him; the only problem is she died 30 years ago. Also, Rick and TC meet a fellow vet who is having a hard time adjusting to civilian life.

A man hires Magnum to investigate his own murder before he is killed. Kumu reconnects with an old friend.

Magnum discovers that his ex, who landed him and his friends in a POW camp, is on the island and planing to steal a fortune in gold.

When the Dobermans dig up what appears to be a human bone, Magnum and Higgins help Katsumoto investigate the murder of his former mentor.

Hannah, Magnum's ex and the fugitive responsible for him and his SEAL team brothers being POWs for years, shows up at his home with a gunshot wound, and wanting his help to find her missing CIA father whose life is in danger. Also, Magnum makes an earnest proposition to Higgins for her to become his private investigations partner.

Magnum must help his defense attorney girlfriend, Abby Miller, when she realizes that the client she successfully defended in a murder trial is actually guilty. Also, TC confronts Kamekona about stealing his helicopter business.

While Magnum helps out his friend Russell Harlan and temporarily works as the head of a hotel’s security, he investigates the death of a guest who was thrown from her room’s balcony while working on a secret investigation of her own. Also, Icepick is released from jail and is trying to keep a secret from Rick.

A guilt-ridden Magnum follows the clues his private investigator friend, Harry Brown, left behind when he was shot while working a case Thomas passed onto him. Also, TC helps Kumu lead a protest against construction on a Hawaiian sacred site.

Magnum and Higgins take the case of recovering the stolen urn of a woman's deceased husband, but they soon find that others believe the urn is worth killing for. Also, Rick and TC confront a man who's been impersonating football legend Andre Reed.

Magnum and Higgins are each hired by a different spouse who are in the middle of a contentious divorce to dig up dirt on the other, and Thomas and Higgins soon find themselves competing over resources. Also, Rick and TC look into the death of an unidentified man and must share the news with his estranged daughter.

Magnum and Higgins help an up-and-coming mixed martial arts fighter who is being pressured by a gang to throw an illegal fight. Also, Kumu is arrested for stealing an artifact from a collector that should be returned to its original resting place.

When a wealthy man hires Magnum and Higgins to find his missing wife, they are stunned when a tragedy occurs as a result of their investigation. Also, Kumu's suspicion of her step-daughter's boyfriend creates a divide with her and Kumu's new relationship.

As Magnum and Higgins work a case to recover valuable stolen truffles, they also must care for a baby left abandoned at the gates of their estate, while Kumu tries to locate the infant’s mother.