As the team makes its final attempt to stop Aggregor, they find an unexpected ally, and one person will make a fateful decision with lasting repercussions.
20 years in the future, Eon attacks Ben 10,000, then disappears. Adult Ben travels back in time fearing Eon will attack his younger self, the present day Ben.
Kevin starts going after Plumbers kids to gain more power. Ben and Gwen continue to argue about how to handle the situation. Gwen tries to find someone who will help her cure Kevin.