It's been a long wait for the final instalment in this series. But it was worth it. This is a remarkable series. From the dark and perplexing mystery of Raven's Gate onwards, the books went from strength to strength. For me personally, the series peaked with Nightrise; the taut spare writing, the brooding atmosphere and the almost unbearable tension were breathtaking. I felt Necropolis was slower to get going, partly because Scarlett was less vividly drawn as a character, but also because the reader was now being spread across a number of points of view. This is an issue that dogs Oblivion too. It was inevitable, as we need to follow all five characters - and yet another point of view is added with Holly. But in Oblivion, although this makes the story long (this is a huge and heavy tome in hardback, all 668 pages of it) the switching viewpoints never make the story slow. It is thrilling from beginning to end; you never quite know where the story is going. Although there are mysterious clues and dark foreshadowings along the way, the tension of how the tale will play out is maintained right to the final pages. At the end of Necropolis, the gatekeepers had been confronted by the Old Ones in Hong Kong and come close to being defeated. They had scarcely met before they were attacked and Scarlett was wounded. With a typhoon tearing Hong Kong and the temple apart, they had no choice but to flee back through the door. Injured and in disarray, they didn't have time to agree a destination and so they were scattered across the globe; Brazil, England, Italy and Egypt. As if that isn't bad enough, the fabric of time itself has been torn and in Oblivion the gatekeepers emerge ten years later to a very changed world. Like in the other books in this series, Horowitz shows he is a master of thriller writing. He rarely wastes words, each description conjuring a clear picture, each step in the adventure carefully woven in. The male characters are as consistent and strong as in the previous books - each of the four male gatekeepers feels like someone you know well. We could do with some more vibrant and kick-ass girls, but they are the one thing that's lacking here. If you've forgotten the previous books (it has been a long time!) there is just enough information in Oblivion to jog your memory without boring you. It's a nail-biting adventure; it is dark, violent and at times really bleak. The novel shows a lively social and environmental conscience which adds to it greatly in my opinion. And the ending is both moving and satisfying. Recommended for teenagers (12 +) and adults who enjoy teen books.