Magic Tree House Merlin Missions: Dark Day in the Deep Sea

In order to save Merlin, Jack and Annie continue their quest for the secrets of happiness. But when the magic tree house leads them to a deserted island, they’re not sure who needs help more – Merlin or them! A shipful of explorers and scientists save them, but the rescuers aren’t looking for the secrets of happiness. They’re looking for…a sea monster! Will Jack and Annie wind up in the monster’s clutches?