Let's Kill Uncle

Let's Kill Uncle is a 1966 color horror film directed by William Castle about a young boy who is trapped on an island by his uncle who is planning to kill him. His only friend is a young girl who tries to help him.

Plot
Barnaby gets hypnotized by his uncle and he orders him to kill himself, throwing himself from a rock to the ocean, but he faints before he can do it and after her mother finds him, he remembers everything but no one believes him.

After that, Barnaby and his friend Chrissie plan to pretend they are hypnotized, and when Barnaby's uncle orders them to jump into the pool with the shark, they wait for their uncle to come out and throw him into the pool.