Over Sea, Under Stone (The Dark Is Rising Book 1)

Three siblings—Simon, Jane, and Barney Drew—discover an ancient map in the attic of their family's rented house during a holiday in Cornwall. This is the first book in Susan Cooper's The Dark Is Rising Sequence. The map leads to a grail, an object of vital importance to the Light in its ongoing battle against the Dark. Throughout history, these two great forces have fought for control of the world. Now, after centuries of balance, the Dark is gathering its forces to rise again, and the children find themselves drawn into the conflict. As the Drews pursue their quest to find the grail, they must contend with sinister human servants of the Dark's power. Their search becomes a dangerous adventure that threatens their lives.