The History Keepers have worked tirelessly for centuries guarding the History Gate to make sure history is not changed. But evil has found a way of going back through time and trying to change the past. So far they have not succeeded but if they do then the consequences will be disastrous. With floods, fires and volcanoes erupting, the History Keepers know it is evil trying to change history but they cannot work out what they are trying to change. From their location in a quiet country village they are in touch with the leaders of the world but it looks as if, for the first time, the History Keepers have been defeated. However, on spring half-term break from their famous boarding school, Jack and Rosie Simmons think they have figured out what is going on, and, with their friends, they are about to embark on a great adventure to stop evil from changing the world forever.