It has a home with its robot pals in an abandoned amusement arcade, and has discovered what true happiness is - although it's still not sure why humans are so leaky and weird ... But when Boot and the gang stumble upon Rusty, an old, broken robot, forgotten in the back of a testing lab, it's time to spring into action. Boot knows there's something special about Rusty - but can they free the old robot and help it find its purpose?