Jack and Annie are off on another mythical mission at the request of Merlin the magician. Luckily, they have a young sorcerer, Teddy, to help them. From underwater caves to a Spider Queen, from mystical selkies to a magical sword, this is a Magic Tree House adventure kids won’t want to miss! Formerly numbered as Magic Tree House #31, the title of this book is now Magic Tree House Merlin Mission #3: Summer of the Sea Serpent.