The boys travel into the future to borrow a tool, but when their future sister Candace finds what they are up to, she realizes that she has the evidence she needs to travel back into the past to bust her brothers. When she returns to her own time, she realizes that she has made a terrible mistake that only she can fix.

Phineas and Ferb build a ocean liner so that Baljeet can go on a romantic cruise with his friend Mishti, whom he now notices is a very pretty girl. Meanwhile, Doofenshmirtz wants to move all the lighthouses to the other side of town so that he can get a good night's sleep instead of hearing the constant noice from the boats surrounding the bay by his headquarters

Dad accidentally sells Candace's favorite doll at a yard sale. Phineas and Ferb become detectives and interview various people to find the doll. Meanwhile, Perry the Platypus tries to get the doll back from his nemesis.