Presenter George Lamb and psychiatrist Sandra Scott watch over rapper Professor Green, TV personality Anthea Turner, strongman Eddie Hall and writer Shazia Mirza as they surrender all possessions and enter the isolation pods.
As some participants are punished for non-compliance, they receive letters from home to comfort them. But one presses the escape button and leaves the experiment.
Stakes are raised for the final hours as the water, electricity and even the lights are turned off. Can the participants see out the remaining time?