By the time Fire and Hemlock was published, Diana Wynne Jones was well established as the writer of a particularly joyous and imaginative style of fantasy that tended to be regarded as suitable for children and young adolescents. Fire and Hemlock was one of her first attempts to move into the area best characterized as young adult fiction. The work is darker in tone than her readers were accustomed to, dealing with a young girls platonic relationship with an older man who shares her love of reading. A counterpoint is provided by the failing relationships of the girls own parents, both with each other and with new partners. Jones is very skillful in creating the ambiguities of the relationship between Polly and Thomas, from Polly’s delight in meeting someone who shares her pleasure in reading and is able to recommend new books to her, to her jealousy when Tom introduces her to Mary Fields, who seems to be his girlfriend. Jones also lovingly creates the world of the teenage girl, neither adult nor child, torn by confusing signals from all around her: the disentangling of childhood friendships, the new interest in boys, and the realization that adults are not to be relied on and can indeed let one down badly. On top of all of this is the magical component of the story, a dark magic entirely unlike that found in most of the story books with which Polly is familiar.
Jones updates one of the most enduring and most menacing of the old ballads without losing any of its power. Instead, she heightens its effect by showing the faeryfolk capable of functioning, apparently with impunity, in the mundane world, exercising power of life or death as they wish, entirely unquestioned. A hero, which is how Polly casts herself, may yet triumph and save the day. The fact that Polly is a hero in many other ways, surviving her parents callous disregard, remains unstated but nevertheless is clear. Jones has never shirked from pursuing an amalgam of magic, fantasy, and the grim reality of everyday life. This novel shows creation of such an amalgam in her best style.