Set on the Isle of Skye around 200 BC, this heroic fantasy novel tells the story of Brennus, a young man who, stifled by pastoral village life, wishes to follow in the martial footsteps of his late father. He has an encounter with the titular Hag of the Hills, a wicked sidhe who promises that his wish will come true—but at a cost. Brennus' life is immediately thrown into chaos as mysterious invaders sweep across the island. He manages to survive the initial onslaught, but a doomed druid's final wish saddles him with a heavy burden.

This novel is exciting and action-packed, featuring plenty of both ancient warfare and bizarre encounters with the supernatural. The author has an archaeological background, and that clearly has enriched the story. Ancient Celtic customs and religion feature prominently; oaths possess an inviolable importance for the characters in the story and slaves are casually sacrificed to the gods in an effort to seek their favor. While the characters presented are largely relatable, I appreciated the occasionally alien mindset revealed by their actions.

First in a duology, this book tells a fairly self-contained story, but certain framing passages hint about a larger, more epic tale. I look forward to reading the forthcoming sequel.