In the movie as Cody is heading home from helping Marahute the Eagle he hears a jingle bell jingling. He follows the sound and sees a mouse tied up on a tree (with the bell tied to it, too) and decides to help free the mouse not knowing that the Mouse is being used for bait to trap an animal. The Baitmouse tries to warn Cody about the trap but Cody doesn't hear him and as he is done freeing the Baitmouse, Cody lands in the trap as he hears an alarm go off. As the Baitmouse climbs out of the trap, he asks Cody if he's okay to which Cody tells him yes. The Baitmouse then goes away and comes back and has a vine that he puts down in the trap for Cody to use to climb out but as Cody is climbing out both he and the Baitmouse hear a truck approaching and the Baitmouse runs into Cody's backpack afraid. When the truck parks out of it comes the poacher Percival McLeach and his pet lizard Joanna who helps Cody of the hole by lowering him his gun to grab onto and pulling him out with the gun. The Baitmouse peeks out of the backpack and when Joanna spots him she jumps on Cody and bites the backpack. When McLeach takes Cody's backpack and tells Joanna to chase after Cody the Baitmouse sneaks out of the backpack and watches as McLeach and Joanna kidnap Cody and take him away in McLeach's truck. The Baitmouse runs to a little house nearby and tells another mouse to send a message to The Rescue Aid Society in New York City so they can help rescue Cody.
He never appears in the the rest of the film, but later it's Cody's turn to try to warn Marahute about the trap.