The Unicorn Trilogy is a series of books by Tanith Lee: * Black Unicorn-The Muggle daughter of a sorceress, Tanaquil, accidentally resurrects the titular black unicorn, who whisks her away to Sea City, where she discovers her father and half-sister Lizra, learns of her own unique magical capabilities, and helps the unicorn return to the perfect world. * Gold Unicorn-Tanaquil is reunited with Lizra, now a conquering Empress, and is coerced into making a war machine in the shape of a golden unicorn work, causing a gateway to a hell-like world to open. * Red Unicorn-Once reunited with her mother, Tanaquil must face her own inner demons in the form of an Alternate Universe, an Evil Counterpart, Tanakil, and the red unicorn that binds them.