Head On: An All Black's memoir of rugby, dementia, and the hidden cost of success'The best sports book I have read in decades' Kevin Norquay, Stuff 'Startlingly honest' Phil Gifford 'A brilliant read. Bold, brave and honest' Mike Hosking, Newstalk ZB Carl Hayman, All Black #1000, once the most highly prized player in world rugby and a giant of the game in every sense someone who was always respected, even feared. But at the end of seventeen years as a professional rugby player, the last eight played with the sole aim of setting up