Ratchet & Clank were working into an inter-universe portal just to visit Jak & Daxter but it made a mistake. They accidentally went to the Angry Birds universe. They have to fight them way through with "The Flock" so they can get back to their universe and fix the mistake. After they got back and fixed it, they went to the Jak & Daxter universe where they met Jak with his best caddy, Daxter. The story continues with Ratchet & Clank: Nick Jr. Cross-over.