A research facility on Mars, operated by the United Aerospace Corporation, sends a distress signal to Earth. A group of Marines, an elite tactical unit known as the Rapid Response Tactical Squad, is dispatched to investigate via a teleportation device called the Ark. Among the marines are Sarge, the no-nonsense squad leader, and John "Reaper" Grimm, a soldier with a personal connection to the facility; his estranged sister, Dr. Samantha Grimm, is one of the lead researchers there. The squad's objective is to secure the facility and retrieve all scientific research and data, with strict orders to contain any potential threat, even if it means eliminating survivors.

Upon arrival, the Marines find the base in disarray, with clear signs of a violent struggle everywhere. As they delve deeper into the facility, they encounter horrific creatures that were once human, now mutated into aggressive, monstrous forms. The squad must battle their way through these creatures using high-tech weaponry and their military training. Unbeknownst to them, the research undertaken at the facility delved into the realms of genetic manipulation and archaeological studies of an ancient Martian civilization, resulting in the catastrophic release of a pathogen that has a terrifying effect on humans. Reaper and his sister Samantha struggle to uncover the truth behind the outbreak, trying to piece together information from the chaotic remnants of the facility's data, which hints at a much darker and more ancient secret buried within the Martian surface.