Magic Tree House: Books 9 & 10
This collection includes:
Dolphins at Daybreak
Morgan le Fay will make Jack and Annie masters of the tree house if only they can solve four riddles -- which will take four books, of course! Dolphins at Daybreak begins the third set of four books in this magical (and increasingly popular) series! Jack and Annie are off in the Magic Tree House again, this time to a whole new world under the ocean. Complete with a giant octopus, a hungry shark, and dolphins to the rescue, this Magic Tree House book delivers an underwater adventure kids can dream about.
Ghost Town at Sundown
Morgan le Fay has promised to make Jack and Annie masters of the tree house if they can solve four riddles. In Ghost Town at Sundown, the Magic Tree House whisks Jack and Annie back to a ghost town in the Wild West of the 1880s. There, they meet a mustang herder named Slim as they search for the answer to the second riddle.