The Simpsons (1989)

S14E6 The Great Louse Detective

The Simpson family scores a complimentary weekend at a spa, but things take a dark turn when Homer is nearly suffocated after a mysterious figure traps him in a sauna. In response, Chief Wiggum enlists a killer's mindset to track down the culprit. Enter Sideshow Bob, Bart's long-time nemesis, who moves in with the Simpsons to assist in the investigation. Together, Bob and Homer uncover that Frank Grimes, Jr.—the son of the man Homer drove mad—is behind the attack. After Grimes is apprehended, Bob turns his sights on Bart, only to find he can't bring himself to harm someone he's grown used to.