Though business has declined further in recent years, his friend Fermín Romero de Torres still finds a place at the bookshop and continues to source rare books while bringing a smile to the faces of the customers.

He purchases the book from Don Sempere Snr and writes an inscription on the cover page: "For Fermín Romero de Torres, who came back from among the dead and holds the key to the future."

It is revealed that Fermín was in prison 20 years earlier with the mysterious stranger as well as David Martin (the protagonist of Zafón's second novel The Angel's Game).

While in prison Fermín, inspired by the story of The Count of Monte Cristo, escaped by taking the place of a dead cell mate, stealing a key from the stranger.

Deception plays a large role in how the characters interact with each other and the influence their lies have on their future (e.g. Fermín's explanation of his past to the Sempere's, Daniel's avoidance of his marital problems).