Eduardo Quintana's life lost all meaning when his wife and daughter were killed in a tragic accident. The once renowned painter wallows in grief and guilt, subsisting on alcohol and drugs, not caring if he lives or dies.

But when a grieving mother asks Eduardo to paint a portrait of the man who killed her son, he finds himself drawn to the unusual commission. He alone understands her need to look deep into the soul of the man who changed her life forever, and he alone can help.

As Eduardo sets out to discover what it takes to know a killer, he is pulled deeper and deeper into Madrid's criminal underworld, where mercenaries, prostitutes, murderers, and thieves are all entangled in a dangerous and deadly web, in which nothing, and no-one, are as they seem.