Chachi is entrusted to close Arnold's, but he forgets to turn off the grill and carelessly tosses his apron on the hot surface. The result is a fire that destroys the drive-in restaurant, traps Fonzie, Ralph and Potsie, and lands Al in trouble with his insurance agent.

When Richie's amateur commercial doesn't bring more customers into his Dad's hardware store, the Cunninghams hire a smooth-talking advertising expert who promises a huge increase in business but who also has a hidden agenda that challenges Howard's business ethics.