This picture book follows a penniless prince named Tim and his only friend, a black horse, who must fall under the spell of the horrible Sea King. The Sea King demands that they bring him a princess from the mountains to be his unwilling bride. The princess has some of her own ideas however. At her wish Tim and the black horse are sent on three quests to delay her marriage, and hopefully defeat the Sea King. The illustrations in this book are eerie, beautiful in a slightly bizarre way. One of the images of the black horse leaping towards a mountain of fire stuck with me through my childhood long after I had forgotten the book's title. I was very please to re-discover it.