Now on his own, Ben sets out to be a solo superhero, with new alien heroes at his disposal, but Grandpa Max has other plans. (Introducing Rook, Malware, Khyber, Nemetrix alien Crabdozer, new Ben aliens Feedback & Blox, Pakmar)
Ben and Rook discover an underground city beneath Bellwood populated with aliens! But who is terrorizing them? (Introducing Nemetrix alien BugLizard, & Ben alien Shocksquatch, Psyphon, Fistina, Bubblehelmet, Liam)
Flashback episode: Young Ben, Gwen, and Grandpa Max visit Azmuth on Galvan Prime. There, they have their first encounter with Malware, a corrupted Mechamorph who's determined to make Azmuth cure him, by any means!
Ben and Rook must stop a giant rampaging alien from destroying Bellwood while dealing with a peace-loving alien-rights activist who doesn't want it hurt. (Introducing Hokestar, Solid Plugg 1st appearance, Pax, Sunder)
When Ben and Rook investigate a mysterious alien ghost ship, they discover that Argit and the Vreedle Brothers are fighting for possession of a doomsday device!
Khyber and his Nemetrix possessed pet have been testing Ben's skills and gathering information. They now use their collected knowledge to finally face Ben in battle.
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.
