While getting his weekly Counteragent shot, Darien becomes infected with an experimental batch of Counteragent. The experimental stuff renders Darien randomly invisible...and it's contagious. First the Keeper becomes infected when she cuts herself while taking blood samples. She goes into Quicksilver madness, and attacks the Official. Both he and Hobbes becomes infected as well. Darien is also going into Quicksilver madness, since the arm with his tattoo is invisible. The Official locks down the facility under quarantine, but goes nuts as well, and escapes. Returning agent Alex Munro manages to capture him, and they discover that Hobbes is uninfected. The mayo on his sandwich was bad, and the bacteria counter-acted the experimental Counteragent. All they have to do to cure themselves is eat similar sandwiches with bad mayo...and get food poisoning for a couple of days.