In this third book in Susan Cooper's Dark Is Rising sequence, Simon, Jane, and Barney return to Cornwall with their Uncle Merry after learning that the grail they had found in Over Sea, Under Stone has been stolen from the British Museum. Will Stanton and his American uncle come to Cornwall as well, and initially there is some tension between the children. The locals are preparing for a celebration in which the women fashion a being from sticks and leaves and toss it into the sea.
Jane's kindness wins the favor of this mystical effigy and it yields its secret the manuscript that will make it possible to decipher the writing on the grail. Although the grail has been stolen by the Dark, it is found and the writing proves to be the prophetic rhyme whose words will be fulfilled in the next books. The story requires some knowledge of the previous books, and only becomes complete after reading the subsequent books. This exciting and beautifully written story is filled with magic and mystery.