Darien Fawkes is a con-man and thief who is captured for a third time. Rather then face California's three-strike law, he volunteers for an experiment conducted by his brother Kevin. Kevin and another scientist, Arnaud, have created a synthetic gland that secrets ""Quicksilver"", a substance that can bend light. They place the gland in Darien's head. He soon realizes what has happened and is none too pleased. Darien is even less happy when they discover the gland secretes Quicksilver into the recipient's brain, and enough of it drives the person insane. Darien learns to control his abilities, and soon discovers that Arnaud is up to something. Arnaud claims Darien is insane when he accuses the scientists, but then Arnaud's mercenaries break in, steal the information on the gland, and kill everyone except Darien. Darien goes to his ex-girlfriend, a doctor who is furious at him because he didn't reveal his past. She refuses to believe he can turn invisible, and then Darien is taken away by

Going to Mexico to investigate Arnaud, Bobby meets his new partner Bobby Hobbes: a veteran spy and near basket-case. They escape an ambush by French-Canadian spies. Meanwhile, Arnaud has had Darien's girlfriend Casey brought down to Mexico, planning on using her as a hostage. Darien goes to rescue her, prepared to kill Arnaud since Darien thinks he'll be going insane shortly. Arnaud plays his trump card: there's a counter-agent that will stave off Quicksilver madness, and he'll give it to Darien if he works for him. Darien refuses, escaping with Casey and blowing up the compound (although Arnaud escapes). Both the counteragent and the formula are destroyed, and Darien goes to visit his brother's grave one more time before going permanently insane. However, the Official meets him there and reveals that his Agency was working with Kevin, and they have the counter-agent as well. As long as Darien works for them, he'll get regular doses of the Counter-Agent. Reluctantly, Darien agrees.