In this unflinching documentary, Louis Theroux delves into the world of anorexia, the UK's most deadly mental illness, where one in every 250 women struggles to survive. Embedded at two London treatment facilities, St Ann's Hospital and Vincent Square Clinic, Theroux witnesses firsthand the devastating grip anorexia has on its victims, blurring the lines between disorder and individual, as he finds himself drawn into a complex dance with this insidious force.