Bear Grylls pushes Stephen Fry to his limits with a series of incredible challenges on a once-in-a-lifetime expedition to one of the most spectacular mountain ranges in Europe. Over the course of two days, high in the Italian Dolomites, Stephen travels on the skids of a helicopter, climbs down a raging 500-foot waterfall, sleeps in a First World War trench and abseils down a towering cliff face. Stephen and Bear face treacherous conditions as a freak summer snow storm hits the mountains, and Stephen must face up to some of his deepest fears. He also talks frankly about some of the other challenges he has faced over the years, including prison, his body image, bipolar disorder and a near fatal suicide attempt. 'My hope is that I will be a little bit more proud of myself at the end of it and at least feel that I've accomplished something.' says Stephen. Will Bear break one of our national treasures? Or can Stephen overcome everything thrown at him and face his demons head on?

• Bear Grylls