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

Magnum is hired by an attractive woman to find the missing will of her late father, who was recently killed in a suspicious boating accident - which she suspects her brother of being behind, in order to steal the will. Working on the case, Thomas finds that former client Susan Johnson – whom he was once locked in a bank vault with – is now a fellow Private Investigator, and is working on the same case – for the brother, who suspects his sister as responsible for their father's death. The two P.I.s are soon locked in a battle of wills as they both race to solve the investigation first, but the pair are forced to put their rather love-hate relationship to one side and team up to solve the case of sibling rivalry...