A team of Finnish divers suffers a devastating loss when two of their friends don't make it back to the surface on a deep dive in an underwater cave in Norway. After unsuccessful attempts are made by international authorities to retrieve the bodies, the cave is closed off. The fallen colleagues are left buried in dark waters. In an act of camaraderie and compassion, the team reassembles in a covert operation to bring back the bodies of their fellow divers, risking their own lives in a secret dive. The team constructs a plan that becomes a pulse-pounding plunge into claustrophobic darkness, gambling with their own safety to honour those who stood and swam by their side.