This is a short story that builds the backstory for Shadow Walker, which I read a few days ago. It's a very quick read and I polished it off in one sitting just before bed.
In some ways, although this is a prequel, it doesn't really matter that I read it after book one. I think that it would work both ways, although you would go into Shadow Walker with a little more of an idea of who Liam is. I have to admit that I was drawn to Liam in Shadow Walker and now having seen him when first faced with who and what he is, I like him even more. This book does answer a few questions, but it has left me with even more. I've got half-formed theories and ideas about Liam, Alana, their families and their situations, but I don't want to go into details here, you'll just have to read the books and form your own.
Having read both books, I'm left wanting more and only hope that I don't have to wait too long for book two in the series.