Monkey Fist learns a prophecy from an oracle that will make the leader of the monkeys "unstoppable". So he searches for the perfect monkey leader, and he find this monkey in Middleton. Meanwhile, Kim's father sponsors a yearly "Rocket Booster Club" meeting at his lab. He's brought Kim to it every year since its inception, but she feels she's too old for the club. (Her club T-shirt is a midriff-shirt now.) But she and Ron go anyway. Once there, Dr. Possible introduces all the kids to a new astronaut - Frederick the Chimpanzee. Ron is fearful of monkeys, and he and Kim leave the building. At the same time, Monkey Fist arrives to kidnap Frederick and take him to the new space station where he can plot to take over the world. Frederick wants no part of this, but relents when Monkey Fist threatens the children present. Meanwhile, Kim and Ron notice trouble when a security guard is missing. They discover Monkey Fist and his Monkey Ninjas, and begin to fight them. Ron hides in a cargo module, which is loaded onto the rocket that Monkey Fist launches to go to the space station. To rescue Ron, Kim and Frederick fly a new experimental space shuttle to the station. There, they defeat Monkey Fist and load him back on the shuttle to return to Earth. But Frederick chooses to stay. His job is to work in the space station; he's just arrived earlier than planned. Ron feels sad, for he's now dispelled his monkey-phobia after Frederick risked himself to save Ron. Back on Earth, Kim turns in Monkey Fist. But the Monkey Ninjas have disappeared. They return to the oracle, and learn that it misspoke. They leader of the monkeys is to be "Ron Stoppable".
—Tony-B4