Ben and Gwen's grandfather has lived an adventurous life and he's not about to let a little thing like getting old slow him down. Ben and Gwen had assumed Grandpa Max was just an ordinary retired plumber, but over the course of their summer vacation, they came to learn that “The Plumbers” is actually an intergalactic peacekeeping force. Max is sworn to keep Ben's powers a secret, but he's also keenly aware of the tremendous responsibility that comes with the Omnitrix.