In a post apocalyptic England, British Scavs (short for scavengers) search through the ruins of London under the watchful eye of the Vlad (Russian) army. They have been looking for "The Artifact" for a hundred years, though no one is sure what the artifact is. Cass's little brother, Wilbur (both Scavs) thinks he has some clues to where the artifact might be. While following one of them, he meets an odd boy, Peyto, in the tower of Big Ben. Cass and Wilbur help the stranger get past the Vlad guards and out of the city, where they meet up with Peyto's friend, Erin. Cass discovers that her two new friends are from a space ship and they, too, are looking for the artifact which was lost from the ship centuries before. The four friends discover they only have 6 days to find the artifact, save the ship, and the world from utter destruction.
There were some things from this story that were pretty far out there. It seemed pretty improbable to me that a whole Russian army would be dispatched for 100 years to look for an object that no one had ever seen and no one knew exactly what it did. That is a lot of resources to throw at a rumor. Then, when the kids find the artifact, it is in the British Museum. As the children walk through the deserted building, all of the displays and artifacts are sitting, intact, under a layer of dust. So we are to believe that London had been desolate for 100 years, but no one had ransacked the museum? Also, the museum is full of hundreds of cats. So what had the cats been eating for the last 100 years?
Despite the logical issues, I liked the book. The characters were interesting and strong. I enjoyed the voice of Cass, who speaks with a strong Cockney dialect and had a really spunky personality. Webb also tackled some interesting ethical issues in the final confrontation. The reader should beware that their is a pretty high body count in this book, so it is not for the squeamish of heart. Over all it was a pretty good sci-fi for early teens. (336 p)