First of all, this is not a masterpiece of literary fiction. There are a lot of flaws, specially in character's development and some moments in the plot that the actions are not at all according with the personality of the characters. But despite these points it's really a very interesting story, it develops from a very commmon report of near death experiences in wich people see a tunnel of light and have a glimpse of what lies beyond. The protagonist starts to catalog these experiences using an eletrical device to make people came back to life (simular to the modern day crash carts), and at some point, in order to validate the research, he decides to take the trip himself. I think at this point the author should have explored more this decision, that seems to me too frivolous and unconvincing. Anyway, when he does it, instead of seeing a tunnel of light and a preview of heaven, he travels to what appears to be hell itself, and comes back a different person, with some lind of evil with him.
To anyone, like me, who is used to read the Max Liebermann's stories (from the same author under the name Frank Tallis), will find in this book a very different way of writing. Paris does not have the same appeal (in the book!) than Vienna in the Liebermann series, and the female protagonist is not at all as interesting as in the other books. This novel has a darker atmosphere, a lot of religious references and has a more crude violence and almost-explicit description of sex scenes, so it's not for imature people at all.
All things considered, it's a small book that worth reading, specially for its originality. I believe the author has much more to offer in the near future.