Chimera was a virus created by Biocyte Pharmaceuticals and its cure is Bellorophon.
Later, Ethan is informed that the Chimera virus is in the enemy hands and the mission begins.
At a horse racing event, Ambrose meets John C. McCloy, CEO of Biocyte. Ethan destroys all but one Chimera sample at Biocyte head office.
Then, Ambrose orders Nyah to pass him the last Chimera injection gun, but she injects herself. Ambrose lets Nyah run wild to spread the virus as Ethan, disguising as Hugh Stamp, Ambrose's henchman, gets the Bellorophon and Chimera before escaping to cure Nyah after killing Ambrose.