Peter Quinell was obsessively searching for the final resting place of the Ninth Legion, supposedly lost when sent north in the 2nd Century AD to deal with some rebellious Picts. The Ninth Legion lay here, thought Peter, because a local boy called Robbie saw and talked to the ghost of the Sentinel who stood guard over the bodies of his dead comrades. The worst of it was that Verity believed Peter, she believed Robbie, and she believed in the Sentinel. And when he stepped in to become her own protector, she believed in him even more.