Anne Bishop, author of the award-winning Black Jewels Trilogy, returns to the Realms for this stand-alone prequel, the setting being a pre-industrial world where magic equals power and social status is pre-eminent, the course of a person's life determined by the color of the jewel one wears as revealed in an occult birthright ritual. The Realm of Hayll is under the rule of the ruthless, sadistic Queen Dorothea who seeks to increase her territory; to do this she controls (just barely) the dangerous but irresistably attractive Daemon Sadi who plays a small but significant role in the plot (fans of the previously written books will be glad to know).

The male protagonist is Jared, a youthful Red-Jeweled Warlord who, captured at 18 and forced to serve nine torturous years as a pleasure slave, murders his owner-queen and escapes, only to be caught and auctioned off into slavery again. A formidable Gray-Jeweled Queen, the female protagonist, shows up at the last minute and purchases him, ostensibly to add to her stable of idiosyncratically selected slaves -- but Jared's new mistress and her entourage are not what they seem. Their true nature is gradually revealed on the way home as Dorothea's forces attack the group, forcing them to take a desperate trip cross-country. The "Gray Lady" turns out to be Lia, a leader of the resistance against Dorothea's domination, a movement centered in the Territory of Dena Nehele where Lia plans to give her now-liberated slaves a chance to live in freedom. Their inevitable gratitude virtually guarantees participation in aiding the fight to be independent.

Along the way to the literally gut-wrenching and suspenseful climax of the story, there is plenty of adventure; romance (between Jared and Lia); dazzling wizardly pyrotechnics and internal workings of Bishop's unique and fascinating hierarchical magic system; and plenty of highly-charged, emotional character development often shown in scenes of totally non-gratuitous explicit eroticism sometimes quite sadistic on the part of the antagonists.

The narrative shifts point of view at intervals from the heroic Lia, Jared and their colorful, distinctive supporters to Dorothea and Lord Krelis, Master of the Queen's guard, equally vivid, fully-fleshed out and believable villains. The plot strands' convergence is skillfully handled, building tension and suspense right up until the end when Lord Krelis and his forces confront Lia, Jared and their intrepid band bolstered by citizens of Dena Nehele, an inevitable encounter after the pursuit/evasion scenarios that provided much of the momentum of the tale.

What makes Bishop's books transcend the formulas of the otherworld fantasy-adventure sub-genre to which they belong are her distinctively conceived, intricate societal and magic structure rich in strongly dark elements balanced by the firm belief in ideals like loyalty and love, and particularly the stories' intriguing, cleverly conceived often amusingly inverted gender roles as exemplified in the eponymous artifact -- an invisible version of the cock-ring used by powerful witches to control their males.

The characters are also especially interesting, Bishop being superb at depicting their essence through dialogue which can often be quite witty or emotionally heartwarming or chilling at the right moments. Then there's the author's overall sublime skill as a writer, blending the darkly macabre with spine-tingling emotional intensity, mesmerizing magic, lush sensuality, and exciting action all set in a thoroughly detailed invented world of cultures in conflict based on ingeniously reversed genre cliches. The Invisible Ring, for newcomers to Bishop's work, will serve as an enticement, whetting the appetite to explore more of the Realms in the Black Jewels Trilogy, while those who have already been entranced by the trio of titles will find herein a satisfying supplement. Either way one approaches this book, it and its predecessors are genuine gems of fantasy much to be prized!