While driving on a Florida highway, a bus of escaped felons rams into the RV. Ben transforms into Stinkfly (though not intentionally) and tries to stop them. With a little help from Grandpa's handy driving, and a magic spell from Gwen, the felons are put back in jail. On the news, the Tennyson's hear about purple lightning delaying a space shuttle launch. Remembering the lightning from the encounter with the werewolf and mummy aliens, they head to Cape Canaveral. At the Space Center, Ben comes under attack by the werewolf and mummy aliens, and new Frankenstein alien. However, why is the purple lightning occurring, and what ties does it have to an old "friend"?

Ghostfreak's return spells disaster for our heroes. Grandpa Max and Gwen must deal with the mummy alien in space while Ben deals with Ghostfreak and Dr. Vicktor on Earth. Ghostfreak then reveals his master plan: he plans to blanket the Earth with Coronium so that sunlight will not reach the planet so that he may rule. With the power of a new alien in the watch, can Ben stop Ghostfreak, and save Grandpa and Gwen?