The Prīmulī Prophecies
METATRON'S CUBE

Max and Jennie Gunnarsson are sent on their first mission as Prīmulī. They are to travel through time and locate Edmund, the klutzy apprentice of King Arthur's Merlin. This Edmund has unearthed the fabled cube, and is using it to travel through history, where he unwittingly starts to create alternate timelines.

Not only must the Gunnarssons find Edmund, they also have to undo the damage he has wrought before these alternate timelines become permanent and disrupt the decided order of the universe.