chunk: Ethan Hunt is alerted by the IMF that someone has used his identity to assist bio-chemical expert Dr. Vladimir Nekhorvich to enter the United States, only to kill him in a subsequent plane crash. Nekhorvich, an old friend of Ethan, had forewarned the IMF of his arrival, planning to deliver to them a new bioweapon, Chimera, and its cure, Bellerophon. He was forced to develop these by Biocyte Pharmaceuticals. IMF determines that rogue IMF agent Sean Ambrose is responsible. IMF assigns Ethan to recover the virus and its cure. It also insists that he recruits Nyah Nordoff-Hall, a professional thief presently operating in Seville, Spain. Later, Ethan finds out that she is Ambrose's ex-girlfriend.