The Stooges are investigators for the Onion Oil company, whose service stations are being robbed by a gang of crooks. On the job, the Stooges provide nothing less than first-class service. However, most of the services are not typical of your standard gas station (shaves, manicures and cologne), and they still somehow manage to be robbed when their backs are turned. Tracing a trail of motor oil to the crooks' hideout, the Stooges demonstrate boxing skills far more effective than their earlier detective skills.