The Fathomless Caves comes with a comprehensive glossary containing a detailed list of characters and other terms coined by the author so that acquaintance with the preceding five books, although preferable, is not totally necessary for enjoyment of this magical tale set in a medieval world.

While the royal court of Eileanan celebrates Beltane, their revelry is turned to ruin by the unwarranted attack of the Fairgean, a vicious sea-faring partially aquatic race. They wreak terrible destruction and murder hundreds of innocent inhabitants of coastal hamlets and villages, and the king, Lachlan, together with his nobles, swear to pursue them and settle their ancient enmity for once and all. He calls in fealty from his allies and with their aid and the help of his bride, Iseult, and her witch twin, Isabeau, he seeks to beat the Fairgean in a race to their traditional grounds near their sacred caves. His military strategy calls for him to make a great sacrifice, that of releasing his wife from the geas that bound her to him and allowing her to return to her native snow mountains on the Spine o' the World to negotiate passage for his troops through a substantial shortcut controlled by her people and their neighbouring dragons. He and she are each torn with uncertainty as to whether the love she bears him and their children will be sufficient to resist the incessant pull of the freedom of the cold clear spaces in her mountain home.

Travelling with Lachlan's army is Isabeau, and much of the tale is told from her perspective: her struggles to attain the understanding and depths required to become a sorceress and her battles against the temptation of the handsome and charming Dide, juggler, jongleur and faithful companion to the king. She has a heavy burden to bear, as her bonds with her twin make her aware of Iseult's feelings; she must care for the princes in her sister's absence, work at her sorceress studies and make decisions on which hinge the outcome of the impending war. Together with the doomed and aged Seeress Meghan and crippled and short-tempered Gwilym the Ugly, she must use her magical skills to protect her adopted people, in the knowledge that the Fiery Comet signals the end of Meghan's long life and has some unknown bearing on her terrifying vision of a monstrous tsunami drowing the land and all in its path.

The half-Fairgean sorceress, Maya, is captured and then freed by Nila, prince of the Fairgean court, allowing her to seek out her daughter Bronwen, who is under the protection of Isabeau. His action and their talk have far-reaching effects with regard to the battle. Maya, seemingly unrepentant for her history of evil and murderous acts, offers to help in the forthcoming war, but Lachlan understandably refuses to trust her, causing distress and bitterness to Bronwyn and Maya herself.

Dialogue is Scottish in style, and for those not at ease with that tongue, may be difficult to understand at first without constant references to the glossary.

Kate Forsyth keeps the story rolling along at a fair pace. She establishes the nuances of character early on for those unfamiliar with the other books, so that readers soon becomes involved in the lives of the court of Eileanan and are keen to unravel the events affecting the people. The Fairgean remain mysterious and much feared; we mainly see them through the eyes of the people of Eileanan and are only privy to a few brief glimpses into their culture, which is harsh and unforgiving.

The Fathomless Caves is a good yarn, balancing action, suspense and emotion, magic and mystical species and retaining my interest to its conclusion. I'm not sufficiently impelled by the tale to race out to buy the previous five books, but those already hooked on the series should not be disappointed.

- Rambles
written by Jenny Ivor
published 1 March 2003