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 is hired by a woman to prove that her son didn't kill his girlfriend and has only 24 hours to do so before the accused accepts a plea deal. Also, Rick and TC try to recover stolen appliances that were donated to a wounded veteran.

When Magnum and Higgins get “yacht-jacked,” Higgins is shot and she and Magnum are stranded at sea, struggling to reach land before she bleeds out and the culprits return to finish them off.

Kumu and Higgins are in danger when Robin's Nest is under siege by mercenaries storming the estate in order to find out the true identity of the White Knight, Robin's muse and literary hero. Also, Rick and T.C. helps one of Rick's employees when his car is stolen, and Higgins finally gives Magnum an answer about if she'll become his partner.

Magnum and Higgins' new partnership is tested when they disagree about being hired by a woman who wants them to recover her $3 million in stolen drug money in order to save her husband's life.

Magnum is called up from the reserves for a top secret mission, but his friends are stunned when they learn that the mission is a lie and Magnum has been set up.

When Jin learns that an innocent woman is the target of a deadly hit, he asks Magnum and Higgins to help save her.

As their wedding day approaches, Magnum and Higgins help a modern-day Robin Hood who, thinking she was helping a school obtain needed supplies, unknowingly stole illicit drugs. Also, Rick helps a retired soldier with the difficult task of re-entering the work force as a civilian.

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.

As Magnum, Higgins and TC try to pull one over on a customs agent to get Higgins a green card, armed gunmen suddenly storm the federal building and start taking hostages.

When a Marine Corps vet’s SUV is stolen with her service dog inside, Magnum and Higgins must find the car, the dog and the car thief who they believe may be an escaped kidnapping victim. Also, when TC is sued by a disgruntled customer, he asks Rick and Jin to help prove that he’s being scammed.

Magnum’s Uncle Bernardo visits and reveals a shocking secret about Thomas’ mother. Also, TC asks Higgins for help when he realizes he may have witnessed a potential murder from his helicopter, Higgins decides it’s time to tell Ethan the truth about her past and TC offers Shammy the opportunity to become a pilot.

Magnum and Higgins work a stalking case involving a man with a past in espionage. Also, Ethan asks Higgins to join him on an extended trip for Doctors Without Borders just as Magnum starts to open up to other possibilities.

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.

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.

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. Rick struggles after an explosion takes the life of someone important to him.

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.

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

Magnum and Higgins are sent on a deadly mission inside a high security correctional center when a ruthless criminal abducts Katsumoto and his ex-wife, Beth.

Magnum and Rick make a shocking discovery in the Capt. Greene case. Higgins and TC head to Maui to help an eccentric billionaire find the owner of a pesky drone that has been harassing him. Shammy helps Kumu after an incident occurs at La Mariana.

Magnum and Higgins take on a case that sends Higgins inside a psychiatric hospital. Katsumoto and his son, Dennis, head to the mainland to look at colleges, but their trip takes a harrowing turn when a run-in with a local turns ugly.

An armed hit team lays siege to Robin's Nest. TC is badly injured while Rick fights for his life. Mid Season Finale

Magnum and Higgins go to work for a dangerous and controversial client. Kumu and Shammy help move TC to a veterans' rehab facility. Rick flirts with a woman who works at the marina.

Magnum and Rick race to find a missing witness who can exonerate an innocent man accused of murder. TC tries to repair his relationship with Mahina after being released from the VA.