Using a fake social network profile under Miss Hoover's name, they discover that Lassen has been chosen to ignite the eponymous effigy at the year's "Blazing Guy" desert festival.
Homer has forgotten to book a spot, upsetting Marge, but Bart solves both of their problems by suggesting that they attend Blazing Guy instead.
At the festival, Marge drinks a cup of tea provided by a fellow attendee in order to relax, not knowing that it contains hallucinogens which cause a prolonged delirium.
The Simpsons start for home but inadvertently forget Marge, who finds herself alone in the desert and the festival long over once the effects of the tea finally wear off.
[1] Dafoe previously guest starred as a different character in the eighth season episode "The Secret War of Lisa Simpson".
Club gave the episode a B−, commenting that Lassen "fell flat" because Dafoe's reputation as a menacing actor comes from his physicality rather than his voice.