In 2015 freeclimber Tommy Caldwell spent 19 days summiting Yosemite's vertical, 3000-foot Dawn Wall - the hardest climb in history.

It was the culmination of seven years planning and a lifetime's determination.

Here, he recounts how he got there, the falls and set backs (being held hostage, losing his index finger, the break-up of his marriage), the summits conquered and the fears overcome. It is a story about drive, focus and how to achieve the impossible - one toehold at a time.

'Caldwell's story is one of the best. You get more than just a climbing adventure, you get the inside view of how a person can endure crushing setbacks and persist to fulfill a spectacular vision' Jim Collins, author of Good to Great