Jack Mason is a medic for the Alliance, tasked with transporting a cryogenically frozen woman named Karina from the maximum security prison "the Anvil" to Alliance headquarters. While flying over "the Zone", Mason's ship is shot down by a surface-to-air missile, crash-landing to Earth. Mason is accidentally infected with the mysterious transgenic virus Karina is carrying, who escapes in the chaos that follows as Scavengers arrive at the crash site attempting to capture her; the pilot, Stubbs, is killed in the fracas but Mason manages to outfight them. Mason suspects an unusual nature behind the Scavenger attack, as they were not known to possess surface-to-air missiles.