After a tragic space mission, astronaut John Corcoran crash-lands back on Earth. Despite being presumed dead due to a fatal heart rate, his body remains mysteriously preserved without decay. Taken to a nearby base for examination, John suddenly revives, shocking both the medical team and his fiancée, Julie Simmons. As scientists attempt to understand how he survived, they discover alien cells in his bloodstream. Unbeknownst to them, John's resurrection was assisted by a hidden extraterrestrial.

As tensions rise within the team, they soon encounter a hulking, humanoid creature lurking around the base. It quickly becomes evident this alien entity is linked to John's condition. Amidst the fraying nerves of those involved, including his friends Dr. Alex Wyman and Dave Randall, fear contends with curiosity as they face a life-threatening dilemma: the creature's intentions and the alien influence over John remain unknown. Struggling with internal and external conflicts, the team must decide whether to treat John as an ally or enemy while planning their next move against the invasive species that threatens their very survival. Tensions peak as they race against time to confront a growing menace that holds secrets beyond anything they have encountered before.