What to read after The Doom Stone?

Jackson is looking forward to visiting his aunt who has been busy working on an anthropological dig at Stonehenge in England. Jackson can't wait to finally see the massive and mysterious stone formations in person. But then he witnesses a vicious attack on a young man, and another on his beloved aunt Sarah. A savage beast no one has ever seen before is on the prowl. Now it's up to Jackson and his new friend, Alma, a gravedigger's daughter, to stop the beast. All the clues lead back to Stonehenge, where he and Alma must risk their lives to solve the mystery of the monster stalking the countryside-before it's too late.