Investigative journalist Brian Deer spends five months following Ryan Wilson, one of six healthy volunteers who nearly died after taking an experimental drug in a London clinical trial. The film reconstructs what happened when the men were injected with TGN1412, an immune-system drug being tested for the first time in humans, and within minutes went into organ failure, their bodies swelling as their immune systems went into catastrophic overdrive. Deer interviews Wilson about being brought out of a two-and-a-half week coma to find his fingers and toes blackened and at risk of amputation, and traces how a trial designed to be routine turned into a medical emergency at Northwick Park Hospital. The film examines the safety testing that preceded the trial, the drug company's assurances, and the regulatory gaps that let the disaster happen. It is a case study in how little separates a controlled experiment from a catastrophe, told largely through the account of a man who lived through it.