Liam, Maddy and Sal are all snatched from certain death by a mysterious man called 'Fowler' who offers them the choice: either die as you were supposed to or take my hand and become a Time Rider. I for one would would take the offered hand, and when they do each of the teens is transported from their own time to New York on 10th September 2001. Their job is to watch for any shifts in the timeline and correct them. They live in a time bubble at a pivotal point in history, endlessly repeating 10th & 11th September, endlessly watching the horror of the twin towers, which Sal must get to know intimately so that she can spot any changes that occur which point to an interruption in the timeline. Scarrow is clearly having loads of fun with this book, to a timeline in which the Terminator is President to an AI support unit called Bob, he masterfully grabs the readers attention and holds it throughout the length of the book. History has changed, Hitler won (with a little help from a man from the future) and New York and the world are utterly different but when Derr Fuhrer determines on a final solution for everyone there is a further more severe time shift. Fowler, Maddy and Sal have to deal with a world of devastation whilst Liam and Bob, stuck in an alternate 1957, have to get a message across time to their collegues in the hope that they can save the day. There is no swearing or sex in the book but there is violence both of the shoot 'em up variety and of the more insidious kind, with the creepy creatures that inhabit the end of the world. With the various timelines and length of the book I would put it at a 12+ level, a good book for older teens who may be reluctant readers. This is a ripping yarn that will keep your teens, particularly boys, enthralled for the length of the book and with Time Riders: Day of the Predator due out on 5th August there is no reason why your boys (and girls) shouldn't be riding time for the entire summer.