In an abandoned mansion in the heart of Barcelona, a young man, David Martín, makes his living by writing sensationalist novels under a pseudonym. The survivor of a troubled childhood, he spends his nights spinning baroque tales about the city's underworld. But perhaps his dark imaginings are not as strange as they seem, for in a locked room deep within the house lie photographs and letters hinting at an unsolved mystery.

Like a slow poison, the history of the place and an impossible love bring David close to despair. But then he receives a letter from a reclusive French editor who makes him the offer of a lifetime