The Night Parade — Scott Ciencin

Caught in a war against the creatures of the Night Parade, a desperate ruler enlists the aid of the Harpers to win the battle -- and to rescue her lost heir
 
For decades, the ghastly Night Parade has haunted the sleep of many in the Forgotten Realms. Most thought it was nothing more than figments born of troubled minds. They were wrong.
 
Myrmeen Lhal, the seductive ruler of Arabel, becomes embroiled in a war against the Night Parade, a war in which the Harpers are her only allies. She must triumph against these creatures who live on fear and misery, no matter the cost. But once her forces are bolstered, prepared to fight, Myrmeen learns the forthcoming battle will be more personal than she ever imagined. For the monstrous band's leaders have the daughter she thought dead fourteen years past . . . 

The Night Parade is the fourth book in a series of loosely-connected novels about the Harpers.