After narrowly avoiding being shot during a case, a fortune cookie has convinced Thomas that it's time to repay his friends and associates. As a favour to Higgins in one such payback, he heads to collect a crate of books from the docks, only to find that the crate contains a Japanese stowaway, and promptly upon the discovery he his is attacked by two goons. The stowaway woman is the daughter of an old war comrade of Higgins, who claims to have hidden in the crate to escape from her father in Japan, whom she claims is nowadays a cruel man. Although finding it hard to believe that his old acquaintance has now turned so cruel, Higgins feels obliged to help the girl, who is searching for her American fiancée. Magnum however, is more sceptical, but investigates for himself in case Higgins is becoming entangled in some sort of trap...

Higgins sends Magnum to collect a valuable Kenzan porcelain plate, newly purchased by Robin Masters, from the airport, but the artefact, which was entrusted to the care of a Samurai warrior while in transport from Japan, has been stolen. At first, Thomas thinks the whole thing is a joke, especially when the Samurai, Tozan, claims that the plate was stolen by a ninja, but the situation is for real, and the pair team up to try and find the stolen artefact. But they must work fast, as Tozan's centuries-old culture dictates that he must commit sepuku – which means taking his own life – if the precious plate isn't retrieved...

Magnum is hired by a bank teller from Robin Master's bank to investigate her father, world-famous counterfeiter Herbie ""Rembrandt"" Norton, who has recently been released from penitentiary and whom she suspects has returned to counterfeiting after coming into large amounts of money since his release. Before starting investigations, the pair go to retrieve a book for Higgins from a safe deposit box at the bank, but the woman accidentally locks them in the vault, and with the time-release door and a slowly dwindling air supply, the pair are trapped inside... Meanwhile, spurred on by getting the potentially lucrative case, Thomas had promised to take Rick and T.C. for a luxurious weekend away, but unaware that Magnum is trapped in the vault at the bank, they are annoyed to presume that he has gone without them, and - with T.C. having problems with his girl-friend - they decide to hold a party at Magnum's guest house - which does not go down well with Higgins, who is holding a meditation we