Serial homicide. Stalking. Arson. Gang crime. Who are the people behind these acts of terrible violence? What are their stories? And what is it like to sit opposite them? Dr Gwen Adshead is one of Britain's leading forensic psychiatrists, and she has spent thirty years providing therapy inside secure hospitals and prisons. Whatever her patient's crime she aims to help them to better know their minds by helping them to articulate their life experience. Through a collaboration with co-author Eileen Horne, Adshead brings her work to life in these fascinating, unflinching portraits of individuals who newspaper headlines, TV dramas and crime fiction label 'monsters'. Case by case, Adshead takes us into the treatment room and reveals these men and women in all their complexity and vulnerability. She sheds new light on the unpredictable nature of the therapeutic process as doctor and patient try to find words for the unspeakable. These are stories of cruelty and despair but also of change and recovery. In a time of increasing polarisation, in the face of overcrowded prisons and devastating cuts to mental health care, Adshead speaks to our shared humanity and makes the case for compassion over condemnation, empathy over fear. The Devil You Know challenges what we think we know about evil. It is a rare book that has the power to change minds.