Dr. Juan Antonio Marquez (Miguel Sandoval) is flown in for special treatment at the same time that a John Doe (also Sandoval) is admitted. Marquez's one-of-a-kind blood infection quickly kills anyone else infected including his in-flight doctor, and All Souls' Nurse Cathy Cavalleri (Linda Goodwin). It is revealed that John Doe is the real Juan Antonio Marquez, and that he was replaced by Colonel Avejo (Manuel Tadros in flashbacks) who tortured the real Marquez in prison. Avejo deliberately infects Marquez's niece who is saved with an immunity in the real Marquez's blood.