The Mystery of the Hidden Archer (Earthkeepers, No 4)

It was a miracle. Penny's aunt was kidnapped, taken to the woods, and then miraculously saved by an unseen, hidden archer. The only clue to his identity was a handmade arrow. Eleven-year-old Penny and her friend, Chad, determine to get to the bottom of the mystery.Chad and Penny are members of Earthkeepers, a club of concerned kids trying to do their part to clean up the environment. They're in the north woods of Minnesota to plant trees -- supposedly. In a well-hidden cave they find a coffee can full of newspaper clippings that seem only to raise more questions. Maybe the mysterious stranger is no angel after all! And maybe Penny and Chad shouldn't be out in the woods!Especially since they're increasingly certain they are not alone...