Randall & Hopkirk (Deceased) S01E26 - The Smile Behind the Veil

At the funeral of his friend Caroline Seaton, Marty observes her brother Donald and his wife Cynthia, who seems to be smiling, and he deduces that they have killed Caroline. Jeff is reluctant to investigate so Marty tricks him into visiting the Seaton home, where an attempt is made to kill him. Due to Marty's intervention, he is saved by the real Donald Seaton, who has returned from Australia to find an impostor has taken his name, married his ex-wife - Cynthia - and killed both his father and Caroline for the Seaton estate. The killers throw Jeff down a well but Marty causes two hikers to rescue him and, as the villains are caught and the true Donald takes his inheritance, the partnership of Randall and Hopkirk -Deceased - continues.