In the opening scene Phineas and Ferb go to the museum to discover the ower core for the time machine they built was stolen, intrigued they decide to investigate, Candace wonders what there up to so she follows them. Meanwhile Major Monogram tells Perry that the core was stolen by Dr. Doofenshmirtz to power his Time-inator. The two parties meet at the same place and fight Doofenshmirtz, but the Time-inator malfunctions and transports the group back to the Mesozoic age. Phineas finds out that the pieces of the power core have been scattered throughout time, so it's up to Phineas, Ferb and the rest of the group to find the pieces of the core so they can get back home, but Doofenshmirtz teams up with his past versions to get the core.