In the Sign of the Crystal Ball: The Legacy of the Djinn (vol. 12)

Thirty djinns threaten the world – Alex and friends must stop them! 

Alex and Sahli can hardly believe their eyes! Argus’s sinister plan, which led him all the way to Stonehenge, seems to have actually worked. Because now the friends aren’t dealing with just one djinn anymore, but with thirty! And they all have the same goal: to bring their master to power. The two boys, together with the twins and the shapeshifter Charda, absolutely must stop them. The only question is: how are they supposed to stand up against an entire horde of Argus cattle?