During a trip to San Francisco, the Tennysons discover that doppelgangers of Ben’s aliens are committing crimes around the city. Ben encounters the imposter and discovers that it was really Kevin; their last battle has 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. Four Arms confronts Kevin atop the Golden Gate Bridge, where Kevin’s rage forces one final transformation: a fusion of all of the Omnitrix aliens without the ability to revert back to human form.