As Charlie Dalin set out on sailing’s most difficult race, a grueling 24,000-mile solo journey around the world called the Vendée Globe, he had been keeping a secret from his competitors, his fans and even his own team. He was battling gastrointestinal cancer. To almost anyone else, the idea of competing in the race would seem unhinged. The Vendée Globe had knocked out sailors in peak physical condition. What might it do to someone who was fighting for his life even before the race began? | Wash