A mission to Mars results in a successful return to Earth, but it carries unforeseen consequences. Astronaut Patrick Ross becomes infected with alien DNA during the mission, transforming him into a deadly and predatory hybrid. Ross's newfound instincts drive him to reproduce with human women, spreading the alien DNA and initiating a new wave of terror. Government scientists, led by Dr. Laura Baker, and a seasoned alien hunter, Press Lennox, quickly discover Ross's transformation and embark on a mission to stop him.

As the threat escalates, they enlist the help of Eve, a clone of the original alien-human hybrid, Sil. Eve's connection to the alien species provides essential insights into their biology and motives. Despite initial tensions and fears surrounding Eve's potential volatility, she becomes central to their strategy. Working against time and mounting casualties, the team struggles to contain the spreading alien influence before it becomes an unstoppable plague. Unbeknownst to them, Eve's own transformation presents a double-edged sword in their desperate fight for humanity’s survival.