A rift has opened . . . Worlds are colliding . . . And a knight on horseback has been spotted in Wemworthy town centre. Could mysterious substance deep amber be the source of all the chaos? It's down to modern-world siblings Cat and Simon to join forces with apprentice witch Dora and castle mischief-maker Jem to investigate. But can they mend the rift and find the deep amber before it falls into the wrong hands?