Stan invites his mother to come live with the family after Stan's stepfather dies, and tensions rise when Roger is forced to share his attic with her. But Roger and Stan's mom quickly fall in love and get married, and Stan is forced to deal with Roger as his new stepdad. Meanwhile, Steve and his friends discover a mysterious plane crash while on a bike ride and come across a long-lost script of a "Fast and Furious" movie that they are determined to get made.