When Ben and Gwen argue over a birthday party to occur in the next few months, Grandpa Max is distracted by their quarreling and almost hits a young boy camper. To ensure the boy's life, they head to Camp Opinicon, only to find no people around. As they investigate the premises, they find twins, whom were also hiding from something that may have a connection to the lifeless camp. Grandpa Max readies to leave the area with the children, only to find that the RV's engine is clogged with a mysterious fungus. While the kids take in shelter in a nearby cabin, Grandpa Max is captured. Now Ben must come to the rescue to discover a new alien form, as well as a way to destroy the evil alien Myceloid Monsters and their Fungal Master, and learn the benefits of what sharing can do.
Elenco: Ashley Johnson , Charlie Schlatter , Dwight Schultz , Greg Cipes , Greg Ellis , Jeff Bennett , Jim Ward , John DiMaggio , Kevin Conroy , Kevin Michael Richardson , Michael Dorn , Peter Renaday , Richard Green , Rob Paulsen , Robin Atkin Downes , Tom Kane , Vicki Lewis , Yuri Lowenthal , Jennifer Hale , Kari Wahlgren , Khary Payton , Tara Strong , Claudia Schmidt , Meagan Smith , Paul Eiding , Ulf Söhmisch , Dee Bradley Baker , Fred Tatasciore , Richard McGonagle , Richard Steven Horvitz .