The story takes place at a summer theater in the Berkshire Mountains, where heroine Joan Barry (Carol Bruce) is staging a Broadway-bound musical comedy. Only one problem: two guest stars are shot and killed on two successive evenings, right in front of the audience. Hoping to solve the mystery, detective William Demarest demands that everyone -- actors and theatergoers alike -- return the following weekend to restage the show. But with no major performer willing to assume the fatal guest-star slot, Joan is forced to hire the Three Jolly Jesters (Al, Harry and Jimmy Ritz), Manhattan washroom attendants with showbiz aspirations.