I must have encountered this book in 5th grade, and it made a permanant imprint on my busy little brain. It's not science fiction, more magical realism. This was my first encounter with the horned one, with Merlin, and with bad guys who don't seem so bad, and good guys who don't seem so good.
For a children's book, this was more Lord of the Rings than Chronichles of Narnia
When the Dark is Rising, Six shall turn it back, Three from the circle, Three from the track. Wood, bronze, iron, Water, fire, stone, Five will return and one go alone.