The Gumshoe Kid (1990)

Originally bound for Harvard, Jeff joins the family detective business to save his mother and sister from eviction. He learns the ropes quickly when a gangster hires him to find out if his bombshell fiancee is two-timing him. Shadowing her every movement - and eyeing her every curve - Jeff lands in real hot water, not to mention a hot shower, when thugs kidnap her lover and try to get him. Now they're both on the run - from the mob, from the police (who might be working with the mob), and from his mother (who might pose the biggest danger of them all)!