This first volume of The Dark is Rising sequence begins with the five-member Drew family's arrival for a month-long vacation with an old professor friend of the father's, affectionately called Great-Uncle Merry. "How old he was, nobody knew. 'Old as the hills,' Father said, and they felt, deep down, that this was probably right. There was something about Great-Uncle Merry that was like the hills, or the sea, or the sky; something ancient, but without age or end."
It rains heavily the first full day in Cornwall, or Logres as Merry calls it by its Arthurian name. Bored out of their minds, the three children go treasure-hunting in the house Merry rented for them. Behind a wardrobe, they find a secret passage to an abandoned room. The youngest child, Barney, a keen admirer of the Arthurian legends, finds an ancient scroll that refers to the king and one of his knights, Mark.This happens to be just what some other people, and Merry himself, have sought long for. Indeed, burglars break in during the night to seek it, but they do not find it.
The police put it down to just hooligans, but the children believe otherwise. They tell Merry about their discovery. The man confirms its great value as part of Arthurian history and that Arthur did actually exist. He tells the children the truth about the man behind the legend and of the constant struggle between the forces of good and evil, of which Arthur was one of the strongest warriors during a dark and perilous time. He then informs them of the grave danger they are now in because of what they found with those of wicked intentions to gain it themselves so close behind.
The chase is on. Can Merry and the Drew children outrun their enemies and save this precious artifact?