This summer the author read The Magic Tree House Ghost Town at Sundown by Mary Pope Osborne. The book is about siblings Jack and Annie who travel back in time to the American Wild West of 1880 using their magic tree house. To become masters of the tree house, they must solve four riddles. In this adventure, they are chased out of town by bandits into a canyon and must lie to blend in. They determine the answer to one riddle, "out of the blue, my lonely voice calls out to you," is an echo, which they learn from Slim, a cowboy they meet who was part of the herd.