Acorna's Triumph is a fantasy

Fantasy

Fantasy is a genre of fiction that commonly uses magic and other supernatural phenomena as a primary element of plot, theme, or setting. Many works within the genre take place in imaginary worlds where magic is common...

 or science fiction

Science fiction

Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 novel by Anne McCaffrey

Anne McCaffrey

Anne Inez McCaffrey was an American-born Irish writer, best known for her Dragonriders of Pern series. Over the course of her 46 year career she won a Hugo Award and a Nebula Award...

 and Elizabeth Ann Scarborough

Elizabeth Ann Scarborough

Elizabeth Ann Scarborough was born March 23, 1947 and lives in Port Townsend, Washington. Scarborough won a Nebula Award in 1989 for her novel The Healer's War, and has written more than a dozen other novels...

. It was the seventh book in the Acorna Universe series

Acorna

Acorna is a "Unicorn Girl", a fantasy fiction character created by Anne McCaffrey and Margaret Ball in their novel Acorna: The Unicorn Girl ....

, which McCaffrey and Margaret Ball

Margaret Ball (writer)

Margaret Ball is a science fiction and fantasy author who lives in Austin, Texas. Married and with two kids, she spends time writing, making quilts, embeadery, and taking care of kids at her home. She has a B.A. in mathematics and a Ph.D. in linguistics from the University of Texas...

 initiated in Acorna: The Unicorn Girl (1997). Triumph completed Acorna's biography, which is sometimes called the Acorna series. It was followed by First Warning, sometimes called the first book of the Acorna's Children trilogy.

Plot synopsis

Acorna's lifemate, Aari, has returned home, and the two may together finish rebuilding their home world. Yet the Aari that has returned from his time travels is different from the one who left, to the point that he almost doesn't remember Acorna or the love that the two shared together. During the confusion while Acorna shifts her attention to stopping a violent criminal from harming innocents, the wicked Khleevi return to retake the planet and destroy the Linyaari and conquer their world. It takes all of Acorna's will to rescue the Aari she loves and put a stop to the Khleevi menace.