At Balloch Moss mine in Scotland, water comes through a seam bringing a torrent of mud into the mine and flooding the pit shaft, resulting in 118 men being trapped, with nine missing. The only means by which the rescue team can bring the men out is through some old abandoned workings which are now full of gas and thus will cause delays in any rescue attempt.

Ex-miner and now Coal Board official John Cameron goes down to the trapped men wearing breathing apparatus to explain the situation. As gas is now seeping into the area where the trapped men are waiting, it is decided that there is not enough time to clear the gas out of the workings in order to save all the men. Instead, breathing apparatus is brought down to the trapped miners who then have to walk through the old workings a small number at a time. Those miners still down in the pit have to retreat further into the workings to avoid the gas while awaiting their turn to use the breathing apparatus. After thirty-six hours in the mine, all the trapped men are successfully rescued, with the exception of those who were missing.