A seasoned mechanic is tasked with keeping an interstellar ark operational as it escapes a dying Earth, carrying the last remnants of humanity. However, aboard the vessel lurks a deadly shapeshifting alien intent on exterminating the passengers. With time running out and the stakes higher than ever, the crew must devise a plan to confront this relentless threat. As they battle for survival, the tension escalates, forcing them to confront not only the alien menace but the fragility of their own humanity.