When Dr. Psychobos steals a part out of the Omnitrix, causing chaotic side-effects, it's up to Ben, Rook, and a small team of Plumbers get everything back to normal.
Gwen and Kevin pay Ben a surprise visit, but does Kevin's strange behavior have anything to do with an angry Tetramand princess, or her father's fleet of warships prepared to attack the Earth?
When their fishing trip in Undertown takes a bizarre twist, Ben, Rook, and Grandpa Max, begin their search for a ship-bottling alien pirate who has captured Magister Patelliday.
Rook brings Ben to his home planet to meet the family. Unbeknownst to them, an old foe is raising an army to steal the planet's most precious resource!