This book is the third in the Young Merlin series and finds him struggling with his inner demons as well as those from the past and in the present. He learns that Vivien is in the Ninth Dimension; hoping to be crowned Queen at castle Camelot. By the use of this alternative reality she plans to change the past and erase the whole of the Pendragon dynasty, a cause that is very close to Merlin's heart. Thus the crew of the Endeavour must face danger in a set of strange alternative realities as they try to reach the Ninth Dimension safely and stop Vivien from changing the past, the present and the future.