A man who was drinking at a bar in Wisconsin wakes up on a beach in Hawaii covered in blood two days later. Thomas admits to Rick that he has feelings for Higgins, which isn't a shock to Rick. Katsumoto calls and tells T.C. that Cade's grandmother wants to meet with Cade. T.C. insists on meeting her first. Greg Nettles, the man from the beach, hires Magnum and Higgins to find out what happened. He found a recently fired gun on him when he woke up. Cade's grandmother, Donna Jensen, gives T.C. a hug. The blood on Greg's shirt is from felon Trevor Lyttle. He recalls struggling with Lyttle and firing his gun. Juliet finds Greg's wrecked rental car. Greg recalls the crash came before his struggle with Lyttle and that the woman Angie also was in the car. Greg was used to pick up something from a safe-deposit box. The box belongs to Frank Medina, with Greg listed as the beneficiary. At Medina's house, Greg spies a photo of him and his grandfather, who he hasn't seen in 20 years. They find Medina dead. Katsumoto, Lia, Magnum, and Higgins piece discover that Medina was behind a 20-year-old diamond heist. Cade meets his grandmother. He rejects her for not trying harder to help his mother. Angie's father was Medina's partner in the heist. Angie and Lyttle don't have the diamond. They abduct Greg from the hospital. Greg swallowed the diamond, which is causing his stomach pains. Katsumoto and Lia get to the motel just in time to save Greg. His grandfather left a note for Greg in the safe-deposit box. T.C. gets Cade a plane ticket so he can visit his relatives in Tennessee. Juliet goes to see her shrink. She admits she can't get Magnum off her mind.