Danger Force is hired by Rivalton's Duke Wellington to protect him and his ponytail from his uncle, Archduke Fernando. It seems like easy money, until they find out The Archduke has hired Ray and Henry Hart to capture Duke.

Chapa, Miles, Mika, and Bose are thrilled to have landed dates for the once every twenty-years SwellMelonFest until threats come in prompting Ray to make them work security. The threats become a reality when the kids must fight The Cell at the event.