In the opening episode of The F.B.I.'s fourth season, Inspector Lew Erskine (Efrem Zimbalist Jr.) and his assistant Tom Colby (William Reynolds) go undercover to trap master spy Lorenz Tabor (Louis Jourdan). Ingredients essential to the intrigue are a bus ticket, a cryptanalysis, and a dead man's hearing aid, which is actually a miniature "holding tank" for top-secret microfilm. Featured in the cast are Nancy Kovack, later the wife of symphony conductor Zubin Mehta, and future Hill Street Blues costar James Sikking.