Homer is demoted to supervising interns, among whom is go-getter millennial Mike, a 35-year-old who asks Homer to be his mentor. However, when Homer inspires Mike to start a business of his own, the two find themselves being chased by the mob.

The 30th Treehouse of Horror features a demon Maggie, a mission to rescue Milhouse from another dimension, dead-Homer's spirit trying on some new bodies for size and Selma finally finding love in an unlikely place – the alien in the basement.