Susan Cooper 
Silver on the Tree [EPUB ebook] 
The Dark is Rising sequence

The six servants of the Light — the Drew children, Will, Bran and the mysterious Merriman — have reached their last, desperate fight against the forces of the Dark. They face one final, daunting task: to find the crystal sword. Their search will lead them from their own world to the haunting, magical Lost Land between sea and shore — and they will each stare death in the face before the battle’s final moments.The fifth and final spellbinding book in the highly acclaimed Dark is Rising sequence.