Vertical Blue, 2023, the moment the doping scandal erupts. The competition organiser, William Trubridge, recounts his plan to catch the dopers – and Lydia investigates the fallout of a very controversial drugs bust.

The CEO of the United States Anti-Doping Agency – and the man who caught Lance Armstrong – has advice for Lydia. It's not what she's expecting.   

An anti-doping officer tells Lydia that drugs are only considered a problem in freediving on social media, and in podcasts. She learns the problem is bigger, and more complex, and more corrupt, than she realised.