An international underwater observation program, led by Chinese scientists, is under attack by an unknown danger, and its deep-sea submersible lies disabled and trapped at the bottom of the Mariana Trench. With time running out, former Naval Captain and expert deep sea diver Jonas Taylor (Statham) is recruited by Dr. Zhang Suyin, lead oceanographer of the program, for what is likely a suicide mission.

Years before, Taylor had encountered this same terrifying threat, which forced him to abort his mission and abandon half his crew, resulting in disgrace and a dishonorable discharge. Now, Taylor must confront his fears and risk his own life to save everyone trapped below ... bringing him face to face once more with the apex predator of all time.