Commander Stoner's psychologist brother-in-law, Arthur Ainsley, visits the Appleby and comes to the conclusion that the crewmen aren't really happy -they're just hiding a deep-seated depression.

O'Toole invites Prince Pussik of Tiboria, who is also his country's Grand Admiral of the Navy, aboard the Appleby but he soon regrets it - the visitor loves to give orders, he's only 12 years old.

When the last film reel to the mystery movie the crew is watching is missing they do all possible to find the ending. Extra motivation to find out who the murderer is results because of the bets which have occurred while waiting to solve the mystery.