Magic Tree House Books 37-40 ─ Dragon of the Red Dawn/Monday With a Mad Genius/Dark Day in the Deep Sea/Eve of the Emperor Penguin

This four-story collection includes:

Dragon of the Red Dawn
Merlin the magician will not eat or sleep or speak to anyone in Camelot. What can be done? The enchantress Morgan knows who to ask for help: young Jack and Annie of Frog Creek, Pennsylvania!

Monday with a Mad Genius
They know they have to search for one of the four secrets of happiness to help Merlin the magician find joy in his life again. And so they head off in the magic tree house for Florence, Italy, in the early 1500s to spend the day with one of the greatest artists and inventors of all time-Leonardo da Vinci!

Dark Day in the Deep Sea
Jack and Annie have to find one of the four secrets of happiness to help save Merlin the magician. But when the magic tree house whisks them off to a misty island in the middle of nowhere, they wonder how they will find anything. As the fog lifts, they see a huge three-masted ship-could it be a pirate ship?

Eve of the Emperor Penguin
Jack and Annie continue their quest for the secrets of happiness-secrets they need to save Merlin. This time, the Magic Tree House takes them to the one continent they haven't visited before: Antarctica! What can they hope to learn about happiness in such a barren place? Only the penguins know for sure...Jack and Annie are about to find out!