 Disgruntled delivery driver Sam Cowley dons a mask and commits armed robberies at different supermarkets owned by his boss, Cliff Parker. Cowley comes under suspicion when Dan Mathews learns that he recently "lost" his master key to all of Parker s markets. Cowley believes he can outwit Dan by changing his procedure and robbing the previously-victimized Lauby Market. Officer Johnson spots Cowley at the Lauby Market immediately after the robbery and Dan subsequently finds the stolen money and the mask at the Cowleys  home. The Cowleys temporarily escape when the reluctant Alberta Cowley holds Dan at gunpoint, but they soon find themselves stymied at a roadblock set by Officer Johnson at Dan s direction.