The movie begins with the arrival of an evil alien brain from the planet Arous on Earth. The brain, possessing immense power and intelligence, takes over the body of a scientist named Steve March and begins to use his knowledge to further its own goals.
As the brain takes control of Steve's body, it becomes apparent that it has sinister intentions. The brain has plans to conquer Earth and rule over humanity, using its vast intellect and abilities to dominate the planet.
The government becomes aware of the brain's presence and attempts to stop it before it's too late. However, the brain proves to be a formidable foe, possessing incredible mental powers that make it almost invincible.
As the situation becomes more desperate, Steve's girlfriend, Sally, and a fellow scientist, Dan Murphy, team up to stop the brain and save humanity. They devise a plan to destroy the brain and restore Steve to his original state, but their efforts are met with resistance from the brain's powerful mental abilities.
The movie reaches its climax as Sally and Dan engage in a final showdown with the brain, using their own intelligence and ingenuity to outsmart the alien invader and save the world from destruction. In the end, they succeed in their mission, but not without sacrifice and loss. The Brain from Planet Arous is a thrilling science-fiction adventure that explores the dangers of unchecked power and the importance of human ingenuity and determination in the face of adversity.