If you know how the Great Fire of London starts, you can stop it from happening ... can't you? Joe Hopkins has been visiting the Tower of London when he slips through time. He finds himself in a city which is dirty, dark and chaotic. Relieved to be welcomed once more into Lucy's home, he is horrified to find the Great Plague has killed half her family. Worse still, another great danger looms, a danger only Joe can see. With his knowledge of the Great Fire of London, he knows he must try and stop it from happening. But before he can, he stumbles across another plot more deadly to England than the fire itself.