Alex and his dog Patch are out for a walk when the boy discovers a little toy mouse dressed in a red vest. He falls in love with the tiny creature -- promptly named Reggie -- and takes it home. Soon, "lost mouse" signs appear in Alex's neighborhood, but he ignores them -- after all, anyone who could lose such an adorable thing must deserve to lose it. His friend Brian tries to convince him to return the mouse to its heartbroken owner, but Alex won't...