The Good Magician Humphrey is still missing and Prince Dolph is determined to find him. Though he is armed with the power to become any animal he chooses, his royal parents insist that he bring along a companion—and his skeletal friend Marrow Bones seems like the perfect choice.

Soon Dolph and Marrow are on a rollicking quest from Humphrey's castle to a mysterious island where they must seek out the elusive Heaven Cent. Along the way they encounter bone-hungry harpies, mean-spirited merwomen, and the beautiful Princess Nada held captive by ogres.