Choose Your Own Adventure 19: Forecast From Stonehenge - R. A. Montgomery

You are an explorer and a junior detective and you've just returned to your home in London, England. The solstice is approaching and you follow a tip to Stonehenge in search of the missing heelstone. Is this mysterious contact tied to a dangerous vision of the future? Will you be tricked by the fairies? Can you entice the magical tree sprite and outwit the scary giant?