Ben 10 Season 4 Episode 13 Goodbye and Good Riddance ( Air Date 2008-04-15 ) Genre Animation, Sci-Fi & Fantasy, Action & Adventure, Comedy, Kids category. Overview "The summer finally ends. Ben and Gwen have to go back to their normal lives. Grandpa Max tells Ben to keep the Omnitrix a secret from everyone, even his parents. Ben agrees, but Vilgax arrives and he'll stop at nothing to get the Omnitrix.".