In war-torn London, a group of children stumbles upon a mysterious pocket watch in an old bookshop, only to be thrust into a hidden magical world where time bends and history is fluid. But they are not alone. A secret Nazi occult division, The Black Sun Society, is hunting for the watch's power to change the course of the war. With mythical creatures as allies and danger at every turn, the children must unravel ancient riddles and outwit the enemy before time runs out.