With books like Theo Caldwell’s Finn the Half-Great and Holly Bennett’s The Warrior’s Daughter, it seems we are in the midst of a Celtic mythology boom in Canadian YA writing. Judging by those books – and by Shapeshifter, the new novel from Peterborough, Ontario’s Bennett – this is a decidedly positive thing.

Shapeshifter expands the story of Sive, the young deer-woman who became the first wife of Finn mac Cumhail (better knows as Finn McCool) and later disappeared into the mists, captured by a dark druid.

Bennett deftly embellishes Sive’s story while remaining true to its mythic sources. As a girl, Sive discovers that she has the gift of song, an ability to not only affect the emotions of those who hear her, but to actually render them unconscious if she so desires. In early womanhood, she discovers a second gift: the ability to transform into a deer. She also attracts the attention of Far Doirche, a dark druid, who seeks to use her gift of song to gain power. She escapes him by fleeing to the mortal world, where eventually she comes under Finn’s protection and becomes his wife. The novel also fills in the rest of the story, explaining what happens to Sive after she is finally captured by Far Doirche and taken from Finn.

Shapeshifter is a boldly written, tightly plotted, and hard-edged novel. The action, which covers almost a half-century, never flags, and the story is straightforward without being simplistic. The book is unflinching in its emotional effect, which is rooted in its well-drawn characters. While it works powerfully as a standalone story, the novel gains considerable resonance from its mythic roots, and, with the inclusion of a version of the original tale, will serve as a good introduction to Irish lore.