Effie Sayre always believed in fairy tales. Since childhood, she has been haunted by dreams of the Fairy King. A tattered volume of Angharad, a novel by Emrys Myrddin about a mortal girl who falls in love with the Fairy King and then destroys him, is the only thing that gives Effie strength while studying at a prestigious architecture college.

When Myrddin's son announces a competition to redevelop her late father's estate, Effie is sure it's fate.

But the ramshackle Hiraeth estate hides many secrets, and its inhabitants are far from hospitable. There, Effie meets the daring young literary scholar Preston, who is eager to prove that Emrys Myrddin is a fraud.

As the two rivals learn more about Myrddin's heritage, dark forces are not asleep. And when Effie and Preston reveal the whole truth, the crimson waters will overwhelm them...