Aboard a private aircraft, Ron Moody as Dr. Henry Gropinger – a sharp parody of Henry Kissinger – embarks on a goodwill tour of Middle Eastern countries. He misplaces his diary, and with it his sense of direction, spiraling into panic as he realizes he may not know which country he’s about to land in. Stepping from the plane, he greets a congregation in Hebrew, only to be shot dead in a sudden and startling turn of events.
Soon after, the U.S. President, a caricature of Gerald Ford, receives a threatening letter claiming responsibility for the death and signed by “Moriarty,” who swears he has set in motion a plan to rule the world. In response, the president dispatches a top agent to London to coordinate with the world’s leading law enforcement officials and craft a strategy to thwart Moriarty’s ambitions.
Headed by an incompetent Englishman, the committee decides to seek help from John Cleese as Sherlock Holmes, an eccentric private detective with a penchant for certain addictive pleasures. Holmes is charged by the Commissioner of Police to locate Moriarty’s descendant before the mastermind can seize control of humanity, and he’s paired with the descendant of Dr. Watson, a medical doctor who is also an utter fool. The Commissioner is murdered just as he attempts to depart, a fate that seems to stem largely from Watson’s own bumbling missteps.
The pair then travel to Scotland Yard to brief the committee, but before plans can solidify, most of the committee members are felled by a sniper. With their help gone, Holmes devises a bold tactic: invite the world’s greatest detectives to a party in hopes of trapping Moriarty, who will be drawn to confront them all at once. Attendees include Columbo and Hercule Poirot, among others, and the evening unfolds as Holmes and Watson work a crossword while the suspects are dispatched one by one. The killer is revealed to be a perfect doppelgänger of Watson, causing chaos as Holmes struggles to tell the real Watson from the impostor.
After a series of cunning deductions, Holmes identifies the true Watson, and the doppelgänger turns out to be Moriarty’s grandchild — who is, in fact, Holmes’ landlady, Mrs. Hudson. Holding Holmes and Watson at gunpoint, she explains a long-brewing vendetta to destroy civilization in retaliation for her grandfather’s death. She shoots Watson, then proceeds to riddle Holmes with an inhuman number of bullets, which he survives only to reveal he anticipated the betrayal and had Watson load the gun with blanks. As Holmes bazes with a smug victory, Watson confesses that he forgot to switch the bullets; Holmes realizes he’s been mortally wounded, and with a final breath, dies.
