Blue Moon's daffy secretary Agnes Dipesto (Allyce Beasley) has won a free trip on a "mystery" train, in which she and the other passengers participate in solving a mystery. While bidding Agnes goodbye, her bosses David (Bruce Willis) and Maddie (Cybill Shepherd) end up trapped on the train themselves. As usual, wherever David and Maddie go, a genuine mystery is sure to follow--and before long, one of the passengers, famed mystery writer J.B. Hartland (Rick Jason) turns up murdered! Among the guest stars is the ubiquitous Vincent Schiavelli, who at the time this episode originally aired was the husband of series regular Allyce Beasley).
by Hal Erickson synopsis