The Once and Future King Book 1, Chapter 10

The boys follow the path and enter a forest, and are surprised to find a giant man lying in the grass. He introduces himself as Little John, and tells them he is taking them to his master, "Robin Wood"--the real name, he says, of Robin Hood. They find Robin Wood in a huge lime tree, a very tall young man lying with his head in his companion, Maid Marian's, lap. Robin asks the boys to shoot an arrow, and then decides they are up for the challenge he has for them-even though Marian continually says they are too young to be sent. It turns out that a member of their group, Friar Tuck, was captured by the Queen of the Fairies, Morgan le Fay, and only children can enter a fairy castle. Tuck happened to be with Cavall, one of Arthur's favorite dogs, when it happened, and they vanished into thin air. Immediately, Kay and Arthur agree that they must rescue the victims.