Top Gear presenter Richard Hammond and motor racing legend Sir Stirling Moss share the same life-altering experience - they had their lives changed forever by terrible car accidents.

The pair recovered quickly from their respective physical injuries, but the acquired brain injuries of those major impacts meant their minds took much longer to heal. But why should brain tissue take so much longer to repair itself than skin and bone and what kind of trauma does the organ go through when trying to 're-boot' itself?

In an engaging and intimate conversation punctuated by some extraordinary medical insights and archive footage of both of their accidents, the two men exchange their experiences.