The #1 bestselling chapter book series of all time celebrates 25 years with new covers and a new, easy-to-use numbering system!

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 wont 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.