Chase and Ava find an old suitcase filled with strange objects. One of the objects looks like a dragon-headed doorknob... Suddenly Chase and Ava find themselves jumping back in time to King Arthur's castle! They meet the king's wizard Merlin and soon discover what the dragon-headed doorknob really is. It turns out they have an important job to do: They must save the king! But a bad guy is after them... How will Chase and Ava get back home? They will need to act fast to find out! Oriol Vidal's engaging illustrations appear on every page.