Phineas and Ferb decided to help Isabella and Fireside Girls to earn Steam Engines Patch and they headed to the Isaland of sodar with their friends Timon, Pumbaa, C-3PO, and R2-D2. When they got there, they meet a little engine, Thomas the Tank Engine. They decided to help him with the other egines. Meanwhile, Perry was on his mission is to stop Dr. Doofenshmirtz for stealing steam engines. While they're working, they have to face to face is thier nemesis, the evil Diesel 10.