DESC: Jack and Annie, two plucky kids with an intense craving for knowledge, are back and attempting to solve four age-old riddles. If they are successful, each of them will be granted the title of Master Librarian. Their incredible destinations include the depths of the sea, the Wild West, wild life-filled Africa, and even the frigid Arctic Circle. This paperback boxed set includes four amazing, bestselling Magic Tree House titles: #9, DOLPHINS AT DAY BREAK; #10, GHOST TOWN AT SUNDOWN; #11, LIONS AT LUNCHTIME; and #12, POLAR BEARS PAST BEDTIME.