The Return Of The Green Child

A mysterious green girl enlists the help of two schoolgirls in finding and recovering a magical amulet that can be used for good or evil.  The amulet had been brought to our world centuries ago by another green girl and her brother and was considered lost.  It must be returned to the world it came from. They are not the only ones trying to find it.  Someone else wants to find it in order to use its powers for evil purposes.  Can they find the magical amulet before it can be used for evil?