In San Francisco, Ben discovers that look-alikes of his aliens are committing crimes around the city. Ben encounters the imposter and discovers that it was really Kevin; their last battle has permanently given Kevin the ability to transform into the various aliens of the Omnitrix. Kevin leaves Ben to pay for his own crimes performed as Omnitrix aliens, bringing Ben into direct conflict with the ruthless Lt. Steel of the government’s Special Alien Capture Team. Evading Steel, Fourarms confronts Kevin atop the Golden Gate Bridge and fight as Fourarms vs Diamondhead. Kevin is defeated, and then transforms into various other aliens to fight him but is still defeated and loses control of the Omnitrix’s powers during the battle, prompting Ben to walk away. Kevin’s rage at the loss forces one final transformation: a fusion of all of the Omnitrix aliens without the ability to revert to human form. Blaming Ben for the mess, Kevin vows to kill Ben once and for all. Fourarms is no match for the new mutation. Fortunately, Steel had observed the battle and conversation and decides that Kevin is the enemy, knocking him into the water below. Ben and the Tennysons leave the scene with approval from Steel. Aliens transformed into: Diamondhead, Wildmutt, Fourarms.