Follow explorer Bear Grylls and his friend Gilo Cardozo as they prepare to fly over the summit of Mount Everest. They will be strapped onto flimsy paraglide chutes powered by backpack motors, or paramotors as they are known to aficionados.

First, Gilo must single-handedly design and build a paramotor that can go a full 3000 metres higher than any other engine, or indeed paramotor, has gone before. Bear takes charge of their survival strategy. The pair face temperatures of –40°C that will instantly freeze exposed flesh, hurricane-force winds that threaten to dash them against the mountain peaks, and very low levels of oxygen.

As the day of the flight approaches, they face the reality of the challenge ahead and are beset with machine troubles, failed test flights and a damaged engine. At his lowest ebb, Bear has some uncharacteristic doubts: ‘I’d always planned this project to be ambitious but safe; the bottom line is it's ambitious but it's not safe.' Have the pair aimed too high?