Magnum and Higgins take on a dangerous mission inside a high-security correctional center when a ruthless criminal abducts Katsumoto's ex-wife, Beth. Also, T.C. rushes to help Rick when Suzy has unexpected pregnancy complications.

A disoriented man hires Magnum and Higgins to investigate a crime he doesn't remember after he woke up on the beach covered in blood. Also, T.C. is taken aback when Cade's biological grandmother makes a surprise visit, and Rick's feelings for Suzy grow stronger as they prepare for the birth of their first child.

Magnum goes to extreme lengths to uncover the truth about a crime that may have involved his dear deceased friend, Nuzo.

Higgins is in a complicated situation when 12-year-old Ella asks for help cracking a triple homicide that involves her mother. Also, Magnum bonds with Bob, a terminally ill veteran, while volunteering with the No Veteran Dies Alone Program and attempts to reunite him with his estranged family,.

The mother of a suspected bomber hires Magnum and Higgins to locate her teen son and turn him into the authorities. Also, Kumu and Rick help T.C. navigate his guilty conscience when he runs into a past flame.

When Magnum balks at notorious crime boss Osi Shima's request to find his missing son, Magnum learns he's been poisoned and has only eight hours to locate Shima's son to earn the antidote, or else he dies.

A bail bondsman hires Magnum and Higgins to track down a woman who skipped out on her $250,000 bond. When they locate the body of another P.I. who was previously searching for her, they partner with Det. Lia Kaleo on the case. Also, T.C. and Katsumoto team up on an emotional search for Cade's mother.

When Hawaii Supreme Court nominee Judge Rachel Park is being blackmailed, she hires Magnum and Higgins who go to extraordinary lengths to help her out. Also, with the pressure of fatherhood looming, Rick suggests changes to make La Mariana more profitable, but TC and Kumo aren't swayed.

Shammy asks Magnum and Higgins to locate his missing friend, a homeless veteran. Also, T.C. tries to get Cade to return to school, but quickly learns it's not that simple.

A nun hires Magnum and Higgins to investigate a mysterious and large cash donation made to a parishioner undergoing medical treatment at the church. Also, Jin's new dog walking business takes a dramatic turn, and Rick nervously prepares to reconnect with Suzy.

When a woman hires Magnum and Higgins to locate a man she met briefly at a coffee shop and felt a spark with, they learn that he is hiding a big secret. Also, Higgins keeps a secret of her own after she has a romantic dream about Magnum.

A Christmas Eve ransomware attack on the Honolulu Police Department forces Lia to reveal a family secret to Magnum and Katsumoto.

Magnum starts following Higgins to discover what she's been hiding, as she's secretly assigned to infiltrate a group threatening to take down MI-6. Also, Rick struggles after an explosion takes the life of someone important to him.

When Rick is asked to assist with a federal investigation of his childhood friend Robbie, Magnum launches his own investigation to see what the federal agents really have on him. Kumu goes undercover in a retirement community.

A journalist hires Magnum to track down his anonymous source after they mysteriously go dark, and Higgins receives a new assignment from MI-6. Also, Rick's old friend comes to the island, but TC is suspicious of his motives.

When Magnum and Higgins are hired by an anxious groom to look into his bride-to-be on the eve of their wedding, what they think is a simple case of cold feet turns into a web of lies and a life-or-death situation for Higgins. Also, TC makes a touching decision on how to help Cade.

Higgins' therapist hires her to look into why one of her teenage patients died of suicide.

Magnum, Higgins and Rick go undercover at a ritzy country club when a young caddie is fired after being accused of stealing a member's golf clubs. Also, Jin's niece, unaware of her uncle's shady past, asks him to speak at her school.

While Magnum and Higgins reunite and work the case of a construction worker's tragic death, TC and Shammy get skyjacked by a pair of drug runners posing as tourists.

As Magnum tries to keep his new relationship a secret and handles cases solo while Higgins is away, he is tasked with finding a single mom being hunted by two very dangerous gangs. Also, while Higgins is abroad with Ethan, a misstep forces her to assist an old employer, and Rick gets some bad, but also very, very good news.