The story begins with the discovery of a young woman's skeleton found inside the Roman Wall at Sycamore Gap, which had been hiding there for more than a decade. From the start, the reader is swept into a complicated case that pushes DCI Ryan both into solving the crime in front of him and into facing aspects of his own dark past. The author successfully creates a mysterious and dangerous atmosphere using several parallel storylines and shocking discoveries along the way.

The setting of the book can be described as one of its strongest features. It is not just a location but the whole atmosphere created by the author using the amazing scenery of Hadrian's Wall country.

Aside from the mystery aspect, this book also includes a number of funny and romantic scenes, as well as some more vulnerable ones. This way, the author succeeds in developing her characters and providing them with a little more life without losing the momentum. DCI Ryan is still a complex and fascinating character – smart, flawed, and human at the same time. The side characters also provide a great deal of color to this book.

Overall, Sycamore Gap is one of those rare books that are both exciting and engaging. It has been written in such a manner that it is easy to understand and to dive into the plot, so you can easily find yourself completely immersed in this novel whether you have been reading mysteries for years already or you are just taking your first steps in this genre. Sycamore Gap is definitely another success by LJ Ross.