Twins Phoebe and Max are enjoying their superhero lifestyle, but when one 'save' goes awry, the Thundermans are sent back to Hiddenville. While Hank and Barb enjoy their return, and Billy and Nora look forward to a normal high school life, Max and Phoebe are determined to regain their superhero status.
Supervillains Harley Quinn, Bloodsport, Peacemaker and a collection of nutty cons at Belle Reve prison join the super-secret, super-shady Task Force X as they are dropped off at the remote, enemy-infused island of Corto Maltese.