When uptight Deputy Marshal Scott Turner inherits Hooch, a giant unruly dog, his new pet destroys his apartment and seems dead set on destroying his career. Scott is desperate to get rid of Hooch, who seems to behave for everyone but him. But when a witness under Marshal protection is kidnapped, he realizes that the dog he never wanted may turn out to be the key to saving the day.

Scott tracks down a notorious fugitive jewel thief while Hooch gets obsessed with a squeaky toy.