Both the 2019 documentary Last Breath and this new feature recount the true story of a 2012 saturation diving accident, when diver Chris Lemons (played in the movie by Finn Cole) gets trapped 330 feet under the sea, with no heat, no light, and a very small amount of oxygen. Spoiler alert: By a miracle, Lemons lived to tell the tale.

In September 2012, while attempting to repair an oil pipeline off the coast of Scotland, the diving support ship Bibby Topaz lost control of the automated system of thrusters that held it in place above the repair crew. Buffeted by winds and swells, the ship began to drift away from the divers, 300 feet below on the ocean floor.