Higgins sustains a concussion hours before the guests are to arrive for a charity gala at the estate, and begins to lapse in and out of believing he is famed Shakespearean actor Sir Fearing Pangborn; Thomas enlists Rick and T.C. to cover security for the event while he takes up the slack left by Higgins's injury, and has his hands full when all the guests, dressed as famous characters of the 1920s in keeping with the gala's ""Great Gatsby"" theme, begin to arrive hours ahead of the appointed time; a crime wave breaks out when someone dressed in the same Charlie Chaplin costume as Rick is seen fleeing from a guest's room moments before thousands of dollars in cash and jewelry are reported missing and an addled Higgins is the prime suspect in the murder of one of the guests; as he begins to realize that people and events are not what they seem, Thomas takes his inspiration from the six-hour First Annual KHKU Agatha Christie Film Festival he viewed the previous night to solve the crimes a

Thomas is hired by Diane Dupres, who was kidnapped as a child with her twin sister, and who now believes that someone is trying to kill her. Although Rick and T.C. think that the woman spells trouble, Thomas begins to fall in love as he spends time with Diane investigating who might want to harm her. Higgins's old flame, the recently widowed Lady Ashley, travels to Hawaii so that they can be married, but Higgins quickly becomes disheartened by his former love's snobbery. Complicating matters, Higgins botches the announcement of his forthcoming nuptials to Agatha, leading her to believe that Higgins has proposed to her.

Conclusion of this two-part story. Higgins must break the news to Agatha that it's not her that he intends to marry, but he finds that Lady Ashley is not the same as the woman that he thought he knew. Meanwhile, Magnum meets Diane's twin sister Diedre, who claims that her sister is a paranoid hysteric who has been in and out of mental institutions, attempted suicide, and has twice tried to kill her. Diane insists that her sister is the bad one and is just trying to bad-mouth her to put Magnum off of her just as she always has done with Diane's men, and as Magnum tries to find out which of the sisters is telling the truth and just what is going on, he encounters one bizarre twist after another about Diane and Diedre's true identities...