From the hardcover:
L. E. Modeistt, Jr., has developed a wide and growing readership with his popular series The Saga of Recluce. With this new book, Shadowsinger, he completes another masterful tale that will take its place among his best and most popular work.

In the four previous volumes of The Spellsong Cycle—The Soprano Sorcerss, The Spellsong War, Darksong Rising, and The Shadow Sorceress—Modesitt has created a rich and complex world and culture, a truly enthralling magical system based on the use of music to create power, and a captivating set of characters embroiled in wars, diplomacy, and politics and, at the same time, immersed in all the concerns of daily life, including love and romance.

The sorceress Secca, principal foster daughter of Anna, the legendary Soprano Sorceress, has taken on responsibilities and authority far beyond what she felt prepared for upon the unexpected death of her beloved mentor. She has fought battles, led armies, has also, unexpectedly, found love and support in the person of her new husband, Alcaren, a soldier of the people of Ranuak and himself a secret sorcerer in a society where magic is not trusted and sorcerers are often assassinated.

As the new Sorceress Protector of Defalk, she must deal carefully with her willful master and wield her power to save his kingdom and the rest of the free world from the Maitre of Sturinn, his invading armies, his dominating fleets, and his legions of master sorcerers. Faced with seemingly insurmountable odds, she is forced to test her own powers over and over again, invent or rediscover ever more destructive magic spells, and guard herself against treachery, magical attacks, and silent opposition from supposed allies. All this while teaching her husband and her young and inexperienced apprentice the skills they need to aid her in creating spells powerful enough to shake the foundations of the world.

As always, Modesitt draws us into the lives of his characters, makes us feel the dilemmas they wrestle with and the conflicts that tear at their souls, makes us believe not just in the power of magic but also in that of the human heart. This climactic volume of The Spellong Cycle is one of his best books to date and a powerful and dramatic payoff to a magnificent fantasy creation.

From the ARC:
The grand conclusion of the Spellsong Cycle.

This is the second novel featuring the sorceress Secca,the principal foster daughter of Anna, the Soprano Sorceress. It is a direct sequel to The Shadow Sorceress, and the fifth and final novel in the Spellsong Cycle.

Secca has succeeded in delaying the conquest of DeFalk by taking the battle to the enemy and sinking an invasion fleet. Yet even greater dangers loom because she can't be everywhere at once. She is newly married to her ally, Alcaren, the man who saved her life. Now, she must help him reach a higher level of sorcery than ever before. Richina, her young apprentice, must also redouble her efforts.

Fearing a never-ending swarm of attackers from the home islands of the Sturrinese, Secca makes a bold and challenging voyage to those islands and conjures a massive eruption that wipes out most of the power base and populations of the islands. But she must still face the most powerful wizard in the world, at the head of great army and supported by many more wizards than she has ever had to fight before. As uncertain as ever of the extent of her abilities and of her stamina for endless battles, she desperately fights on against what seem overwhelming odds.