Gran has said, "I think, as a writer, it's a good idea to challenge yourself and do what you haven't done before. I could have followed the same template and had a career writing detective novels over and over again".

Instead, she has delivered a powerful sexual literary thriller featuring rare book dealer Lily Albrecht. Lily faces severe financial problems in supporting her husband Abel, "a highly renowned writer of academic theory, criticism and obscure histories", who is immobilised with a rare neurological condition.

When Lily is asked to find an extremely rare early 17th century book, "the most precise and most effective grimoire of sex magic ever written", of which only three copies are thought still to exist, she believes her financial problems could be solved.

Additionally, she might be able to help Abel, as it is rumoured that anyone with the book is granted one wish after completing five, mostly sexual, acts linked to the book. Lily will have to consider how much would you sacrifice for someone you love.

Lily embarks with her friend, University Rare Books Curator, Lucas Markson, with a "charm unusual in book people", to track down a copy of the book. This takes them challenging and dangerous millionaire collector territory in New York, New Orleans, Munich and Paris.

Lily reflects, "It was like the book already had me, and was leading me exactly where it wanted".

Lily and Lucas initially discover fragments of the book and begin attempting the five stages, not knowing their ultimate fate. Lily is a strong character, with Gran depicting her "waking back up to life" through her relationship with Lucas. Sex is a driving force in the plot with Lily's encounters in a French château echoing Anne Desclos's famous Histoire d'O.

Gran has commented, "I found it necessary to actually describe the sex. The writer is left to alternate between the words of pornography - effective in their proper context but a bit silly in a literary thriller about a rare book - and the words of anatomy, ugly in any context but needed to explain what goes where.

"It was a challenge to weave these languages together to try to come up with something like plain, everyday English, and write about sex ... hopefully with depth, honesty and, most frightening of all, vulnerability. I'll leave it up to you to decide if I pulled it off". Most readers will think she has.