Magnum and Higgins’ new clients hire them to find their missing brother last seen on the island, leading to Higgins being shot and TC abducted when a secret case of revenge is revealed during the investigation. Also, Higgins (and Magnum!) are surprised when her surgeon asks her out.

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.

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.

As a major hurricane hits the Island, Magnum and his friends find shelter inside La Mariana, along with two armed killers also escaping the dangerous storm. Also, Rick must confess to TC that he let the insurance lapse on the bar.

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.

When an overenthusiastic neighborhood watch group asks Magnum and Higgins to investigate a shady character living on their block, they are shocked to find that they may have inadvertently stumbled upon a serial killer on the loose. Also, Jin’s new money laundering business leads him to want to help a new friend.

When a young man in need of immediate emergency surgery goes missing with a bullet lodged in his chest, Ethan asks Magnum and Higgins to find him before it’s too late. Also, TC talks to a military recruit who may be enlisting for the wrong reasons.

When Higgins is abducted, Magnum discovers its retaliation related to one of his first cases on the Island, and he, Rick and TC must break out an ex-client from prison in order to save her.

When an Army ranger goes missing after returning from deployment, Magnum learns of the traumatic news he received upon arriving home and must find him before survivor’s guilt consumes him. Also, Higgins and Ethan solve the case of a missing engagement ring while on a mini-break, and Katsumoto tries spending quality time with his teenage son.

When a married woman asks Magnum and Higgins to find her lover’s killer because she doesn’t want to expose the affair to the police, they find that the victim wasn’t who he claimed to be. Also, Rick visits Icepick, whose health has taken a turn for the worse.

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.

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.

A psychic hires Magnum and Higgins to prevent a murder she claims to have foreseen. Also, Katsumoto questions Kumu when her information is found on recovered stolen jewels that once belonged to the infamous Imelda Marcos, and Higgins struggles with whether or not to tell Ethan the truth about her past.

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.