Such a struggle to rate this one because it's beautifully written but... makes for a confusing read. It's better than "ok", but as a pre-series prequel it's not quite the most enjoyable thing.
There's a lady, a headmistress of an English school, named Elisabeth. She's suffering from memories of events that seem to have not happened, or at least not in her current reality, and cravings for bloody meat. One night she is visited by... a talking elk. It tells her she must find and protect a child who is yet to be born somewhere in France. By her lack of reaction, this appears to be fairly normal for her. Why? Something about Immortals and Mortals, Physicals and Psychics... Whatever. She's got a mission, and her Resistance allies are going to make it happen... Somehow.
So maybe you see my problem with this. Off the bat, there's a talking elk. Who/what the "Voice of the Voiceless" is remains a mystery to the end of the book. Who/what Elisabeth and her cohorts are remains a mystery until roughly 50-60% of the way through, and even then it's just a few world-specific terms (Physicals, Immortals etc). What that actually means I'm still not sure. There are those not-memories and references to "one taken from the world" that are just as confusing. There's also something to do with a Purge and the Black Rose organisation, lots of different supernatural types and their tangled affairs, lovers and traitors, magic, darkness, death... And of course, the child who will be born to greatness.
I loved the tone, the polished writing (seriously, amazingly polished), the action, the oddball characters with their prickly relationships... But that inability to explain the background of what was going on and why was a bit of a deal-breaker. I felt frustrated that even by the end I was no closer to getting what all these supernatural world people and organisations were. It seems like a case of the reader's ignorance of the story world being forgotten. Maybe this would work as a prequel to be read after further full Delacourt stories have been released, when the world setup has been laid out.
One day I hope to understand the significance of the talking elk, because there's a lot of love and craft gone into writing this short story. It's just missing the information that would make it all make sense to a Delacourt newbie like me.