The Harts become involved in international intrigue when they infiltrate a ballet company to clear a world-renown Soviet danseur of murder charges.

A friend of Jonathan's dies leaving his widow and son with a valuable assortment of baseball cards. Before the Harts can sell the collection for the family, it is stolen.

Jonathan joins Jennifer at her prep school reunion and is drugged by a former admirer who wants Jennifer for himself.

Jennifer finds herself in over her head at the Grey Gables Health Farm when the doctor is killing guests and replacing them with lookalikes.