Casey Legler: What does it take to emerge from darkness?

Imagine having an extraordinary sporting talent, but finding yourself traumatised by the realities of elite-level competition. Imagine being defined by your gender and physicality in ways that crushed your own sense of yourself. Stephen Sackur interviews former Olympic swimmer turned artist, model and now writer Casey Legler about their pain-filled early life, which included a prolonged battle with alcohol and drugs. What did it take to emerge from the darkness?