The celebrities have been living in the dark for 30 hours, and tensions are already reaching boiling point. Things don't get any easier when two of them are shackled together and forced to spend 12 hours in a 2m x 2m box.

The bunker is taking its toll as the celebrities enter their final days in the dark. There's an electrifying challenge involving pitch-black orienteering and painful shocks, and The Wanted singer Max George has some emotional revelations.

The celebrities' strong bond is threatened by a daunting final task. They all must complete it, or the entire group face having their time in the experiment brought to an abrupt end. And when it's all over, the group vote and the winner is declared.