Mortimer Brewster is shocked to find that his sweet lovable old aunts have been poisoning elderly gentlemen and burying their bodies in the basement. Their unwitting accomplice is Mortimer's benignly insane brother Teddy who believes he is Teddy Roosevelt. Mortimer's' attempts to protect them are complicated by a third brother, the sinister Jonathan, and his accomplice who arrive at the house with yet another body to hide. Mortimer tries to get Jonathan to leave the house, but Jonathan decides Mortimer must die. Tied to a chair and gagged when the police arrive, Mortimer cannot get them to arrest Jonathan without exposing his aunts to the law as well.