Martha Phelps (Margaret Dumont) owns a department store where she seems to be losing money, but when her nephew (Tony Martin) is almost murdered, she hires detective Wolf J. Flywheel (Groucho Marx) to discover what is going on with her store manager named Grover (Douglas Dumbrille). Flywheel and associates Ravelli (Chico Marx) and Wacky (Harpo Marx) begin to work undercover for different reasons. Investigating in various departments of the store causes chaos in bedding, women’s hats, and children’s toys. An inevitable chase around the building sums up the shenanigans, as Ravelli and Wacky have found photographic evidence on Grover hiring assassins to take control of the business.