Who are the Sentinels? They're everywhere, but you've never seen them. The Sentinels are the world's best-kept secret, but that secret's about to come out. When teenager Nicholas Hallow's parents are killed in a mysterious train crash, he has a creeping suspicion that they have been protecting him from imminent danger. Against the backdrop of a summer snowstorm, Nicholas and hardy pensioner Sam Wilkins embark on a treacherous journey in which their pursuers are never far behind. A dark fantasy set in Cambridge, Sentinel is the first book in the thrilling Sentinel Trilogy, which takes place in a world that everybody knows, but few would recognise. Who are the Sentinels? Who is the mysterious godmother? And why is Nicholas able to sense things that other people can't? Filled with action and mystery, Sentinel takes the reader on a terrifying adventure with unconventional heroes and a touch of magic.