Something has gone wrong in a research facility on Mars, and the staff are becoming something unimaginable. All research has ceased and the facility has been placed in quarantine. Dr. Samantha Grimm have called in an elite squad of soldiers led by Sarge and includes Samantha's twin brother, John Grimm. No one is safe inside. As the team advance through the facility, and as they are picked off one-by-one, Dr. Grimm has one question: What exactly has caused this?