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.

Det er gået ned af bakke siden Bob Parr alias Hr. Utrolig var verdens sejeste superhelt. 15 år senere er Bob blevet forsikringsmand, småfed og bedsteborgerlig med kone, forstadsvilla og tre børn. Men Bob får endnu en chance for at trække i trikotten og bekæmpe verdens ondskab, da han en dag bliver indkaldt til en tophemmelig mission.

When a young boy finds a message from his late grandfather, his ordinary family discovers an extraordinary secret about themselves — and the universe.

Taking place after the final episode, the Iggarashi Family and FENIX reunite for one last battle against Giff and the Deadmans.