Lieutenant Frank Drebin of Police Squad is a bumbling but well-meaning detective who returns to Los Angeles after a vacation only to find that his partner, Nordberg, has been critically injured while investigating a drug operation. As Drebin attempts to uncover the truth behind Nordberg's injury, he learns of a plot to assassinate Queen Elizabeth II during an upcoming visit to Los Angeles. The evidence points toward wealthy businessman Vincent Ludwig, who has been using an experimental device to manipulate people's actions through hypnotic suggestion.

Drebin's investigation leads him to Ludwig's assistant, Jane Spencer, with whom he develops a romantic relationship. While trying to gather enough evidence to implicate Ludwig and prevent the assassination, Drebin stumbles through a series of absurd and comedic situations, often causing more chaos than order. Despite his clumsiness, Drebin remains determined to thwart the plot, save the Queen, and bring the criminals to justice.