D4 has long been the focus of many conspiracy theorists. The now abandoned government facility was rumored to have been home to disturbing military experimentation years ago. Believing her son has been kidnapped and is being held in D4, a wealthy doctor hires a team of ex-military mercenaries to infiltrate the mysterious facility. Once inside, what seemed to be an easy money job begins to take a turn. Through a series of encounters, the team discovers they're not alone, and what started as a simple search and rescue soon turns into a fight for survival against something beyond human.