I have to say I was a little disappointed with The Prisoner of Heaven I was really looking forward to more witty dialogue from "Fermin Romero De Torres" and it just didn't deliver. Part 3 ties together The Shadow of the Wind and The Angels game and focuses on Fermin's sort of mysterious past as a prisoner of The Montjuic Castle. We learn a little more about Daniel Sempere's mother's death but we still don't know Fermin's real name. Zafon also introduces to us 2 more sinister villains Selgado and Mauricio Valls.
The tone of Prisoner of heaven I felt in some ways was the darkest of all 3 there just wasn't as much humor or entertaining conversation between the characters as in the Shadow of the Wind, it was all to serious.
I thought the ending to The Prisoner of Heaven was so much better then the Angels game and it does hint to a part 4 which I very much hope there is.