It's time for all-new tricks and devilish treats on THE SIMPSONS annual Halloween trilogy, -Treehouse Of Horror XVI.- The fright-fest begins in - B.I.: Bartificial Intelligence - when the Simpsons adopt David, a newly developed artificial robot son, to replace Bart after he falls into a coma. In - Survival of the Fattest,- Mr. Burns invites Homer and his friends to his gigantic estate for a hunting tournament, but Homer and the gang learn they are the ones being the hunted on -The World Series Of Manhunter- hosted by Bradshaw. In the final Halloween scare, -I've Grown a Costume on Your Face,- a costume contest goes awry when a real witch turns all the Springfieldians into real-life versions of their costumes, leaving Maggie dressed like a witch with the only real power to reverse the spell.

Homer's inability to embrace Lisa's Father's Day book the same way he does Bart's Father's Day Toolman causes Lisa to develop Ddd. Meanwhile, Bart steals the Bart Boulevard street sign and causes a huge pile-up. While Mayor Quimby creates The Safety Salamander spokesperson in response to the accident, the town still forces the ineffective Mayor into a recall election. Homer, longing to win back his daughter's love, takes the spokesperson position, and after a heroic run as The Safety Salamander, he runs for Mayor along with every other unqualified Springfieldian.