Nemesis is a brilliantly written, fast moving, action packed novel set in the early stages of the second world war. This is the third book in a series however the author, Rory Clements, has written this in a way that it can be enjoyed, and understood, without having read the first books although I'm sure many readers will want to read the earlier books once they've read this one. The main character is an American teaching at Cambridge who becomes involved in the mystery surrounding a former pupil at Cambridge. There are many twists and turns in this book and the focus is on those plotting behind the scenes against the allies rather than the actions of the defence forces. The main topic is the attempts by a group to thwart any possibility of the US joining the allies and the extreme measures, and risks, they are prepared to take. This book will be enjoyed by any reader interested in books set in wartime and to readers who enjoy a great mystery.