When Lisa cons Homer into letting her ride the bus alone to the Springsonian Museum for the "Treasures of Isis" exhibit, she gets lost along the way. Wandering around the more down-at-its-heels parts of Springfield, Lisa grows increasingly panicked. When it occurs to Homer that he shouldn't have let Lisa ride the bus alone, he sets out to find her. The finally find each other outside of the museum, but Homer is nearly drowned when the cherry-picker truck he commandeered during his search drives into the river. Lisa saves her dad and together they sneak into the closed museum to look at the "Isis" exhibit. During their trespass, Homer and Lisa bond and Lisa learns that taking risks can sometimes be fun.