Art Wallace

A young doctor returns to his New England home town after a long absence. He visits with the town's kindly old physician, Dr. Cook, a man he has admired since childhood. However, he soon finds out that the old doctor isn't quite what he seems to be, and the young doctor finds his life in danger. (imdb)

A "model cop" kills the mistress of his son-in-law in a fit of uncontrollable anger, then tries to pin the blame on an innocent wino. (cduniverse.com)

Two astronauts travelling across the simian-dominated world with their chimpanzee friend are captured and forced to fight in a gladiatorial arena. Later, they search the ruins of an ancient city for clues to the fate of the human race.

A murdered woman seeks revenge, possesses her husband's new wife. (imdb)

A golem made of mud terrorizes a couple on a remote Maine island. Sportswriter Paul Taylor, after a near-death experience on the operating table, can hear the voices of the recently dead. These voices direct him to people who need help from supernatural dangers. In this story, his mission takes him to a remote Maine island inhabited by a murderous man-like creature made from mud and clay. (imdb)

First follow-up film to the series is 2 episodes back-to-back. In Escape from Tomorrow (1974), the astronauts crashland in their own future, which they discover to be ape-ruled, and they and Galen become fugitives after being tricked into escaping by the ruthless Urko. In The Trap (1974), Urko and Burke are trapped in an underground metro station in the ruins of a city, and must cooperate in order to escape, while Urko learns some uncomfortable truths about humans and Earth's past.