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

Magnum helps Dan, a struggling fisherman and fellow veteran, when his 300-pound tuna worth $350,000 is stolen, and he discovers that the thief needs Magnum's help as well.

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.

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.

While Magnum waits for Higgins to decide if she’ll officially become his partner, he takes the case of a missing wife who witnessed her boss’ murder during a bank robbery. Also, Rick makes a big decision about his career.

Magnum, flooded with memories of his tour in Afghanistan, helps his fallen friend’s brother search for a now-grown Afghan boy who may have been a victim of trafficking.

When Junior is kidnapped as leverage to retrieve the stolen list of undercover CIA agents, and most of Five-0 is rounded up by the CIA to prevent them from interfering, Tani and Quinn ask Magnum and Higgins for their help.

The crossover starts on Hawaii Five-0 S10E12 Ihea ‘oe i ka wa a ka ua e loku ana? (Where were you when the rain was pouring?) (I).

Magnum and Higgins help Rick when his father figure, Icepick , just out of prison and battling terminal cancer, gets double crossed on one last score. Also, Magnum makes one last bold move to help Higgins stay in the country.

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 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.

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.

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.

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 Higgins weigh the risks of pursuing a relationship. Rick juggles being a new father and running La Mariana. Katsumoto tries to figure out his next move.

Magnum and Higgins investigate the robbery of an elderly man suffering from Alzheimer’s. The ohana tries to help TC overcome a past trauma.

Magnum and Higgins enlist Katsumoto to go undercover when a chef at a high-end restaurant goes missing. Kumu works with Cade at the Cultural Center, confronting one of America's darker chapters - the internment of Japanese Americans in the wake of Pearl Harbor.

Magnum and Higgins take a major step forward in their relationship. At the same time, the past comes back to haunt them when a previous suspect becomes their client. TC aims to scale up Island Hoppers. Rick gets a new business partner.