Locksmith (Episode 5373)

Richard Hillman, up to his eyes in debt and his business interests failing, concocted a plan to convince everyone that mother-in-law Audrey Roberts was entering senility and then kill her in a fire in her house which would be put down to an accidental death and her estate would be paid to daughter Gail. To this end, he copied her house keys and entered it on several occasions, moving items round, putting washing out which had been left in the machine, leaving the radio on, etc. Audrey was convinced someone was indeed entering her home when she was out and the Locksmith was employed to change all the locks for her. Richard's plan seemed stymied, until that is Audrey gave a spare set of the keys to Gail and he had a means of access to the house all over again.