The story tells a clever opportunity. On the fifth anniversary of Phineas and Ferb's entry into Phineas' home, Phineas made a large platypus badminton machine, and the two sat in it. By chance, they bumped into Terry who was carrying the two on a mission in a rocket car, and accidentally bounced to Doofenshmirtz's house. Phineas and Ferb got to know Doofenshmirtz and helped Doofenshmirtz repair the "Time-Space Terminator" that they had smashed. It happened that Terry broke into Doofenshmirtz's house at this time. Because he couldn't be discovered by the owner of the house, he had to turn back into a non-threatening platypus. After Phineas helped to repair the machine, the group entered another time and space. That time and space was a three-state area ruled by the one-eyed Doofenshmirtz in a black robe, and Captain Moraine became an assistant under the one-eyed Doofenshmirtz. One-eyed Doofenshmirtz transformed Perry the platypus from his own time and space into his evil subordinate, and at this time Perry also exposed his identity in a hurry. Phineas was very unforgiving about his identity as a secret agent. He regarded Phineas as his family, and family members should not have secrets. One-eyed Doofenshmirtz ordered the mechanical platypus to attack Perry the platypus, and after a fight, he temporarily got rid of him, but Phineas Perry wanted to deal with One-eyed Doofenshmirtz alone but failed and was captured. Phineas wanted to return to his own time and space, but the remote control of the time and space terminator failed, so they went to find themselves in that time and space, but found that the other self was completely different from the original, had no imagination, and didn't know what summer vacation was. So they went to find Isabella in that time and space again, and found that Isabella was an officer of Doofen's resistance army, and Phineas' friends in that time and space also became members of the resistance army, and Candice was the leader of the resistance army. On the other hand, after listening to Doofenshmirtz's description of another tri-state area, One-Eye Doofenshmirtz wanted to use the Time Terminator to launch a large-scale invasion of Phineas' original time and space, but Doofenshmirtz forgot how to start it, so One-Eye Doofenshmirtz had to use Perry the Platypus as a hostage to capture Phineas and the others. At this time, Doofenshmirtz remembered how to transform and opened the Time and Space Gate, but One-Eye Doofenshmirtz sent him and Phineas and the others to feed the monsters because Doofenshmirtz was too cowardly. At this time, Curtis from that time and space saved them and used the Time and Space Gate to escape. After escaping back to their own time and space, they found that Doofenshmirtz's mechanical army had also invaded their home, so they found the secret passage hidden in their home and found the secret weapon left by Perry the Platypus. It turned out to be all the inventions that Phineas and his friends had made during the summer vacation. The people of the two time and space used Phineas' inventions to fight back Doofenshmirtz's mechanical army. Phineas destroyed the main control console of the robots, causing all the robots to crash, and Perry the Platypus also defeated the mechanical Perry and eliminated its evil thoughts. Doofenshmirtz used Doofenshmirtz's favorite toy locomotive to lead him back to his time and space, and was captured by the resistance and Mora. Because Perry had exposed his identity, he had to be sent elsewhere. Kyle suggested using Doofenshmirtz's memory terminator to erase their memories. Phineas was reluctant to delete it because this series of experiences was too exciting, but Ferb reminded him that he could create good memories himself, but Perry only had one, so he chose to delete the memory, and everything returned to normal. (Before deleting the memory, Isabella kissed Phineas)