Five renowned detective personalities, each a parody of a famous literary sleuth, receive mysterious invitations to a secluded mansion owned by the eccentric millionaire Lionel Twain. Twain, known for his unconventional antics, promises them a challenging weekend where he will commit a murder at midnight, daring the detectives to solve the crime for a substantial financial reward. Each detective arrives with their unique quirks and skills, accompanied by their sidekicks, building a quirky assembly of characters in the peculiar and foreboding mansion.

As they gather, the mansion's oddities begin to reveal themselves: secret passages, eerie sounds, and a butler who appears blind. Tensions rise as the group interacts with Twain, who mocks their abilities and sets the stage for the planned murder mystery. The detectives start by investigating the mansion and interrogating one another, uncovering various clues and deceits that increasingly complicate the case. As the appointed hour approaches, they're forced to confront both their own insecurities and the puzzles set by Twain, leading to an intricate web of deception and humor that challenges their deductive prowess.