Death Becomes Her (S01E06)

Siblings Nancy and Tom have long been intrigued by their wealthy mother's friend, Marjorie Congdon. However, when Marjorie becomes a prominent figure in their lives, they find themselves caught up in a whirlwind of strange and unsettling crimes. As the situation escalates, Marjorie's true nature emerges, transforming her into a nightmarish stepmother, wreaking havoc on their once peaceful existence.