The Spider Queen - The Space Merchants Series, #5

When an alien species attacks the Talpa Sector, Teagan leads a fleet of warships across the vastness of space to rush to the aid of its peaceful inhabitants. However, being thrust into the center of an alien war is the least of her worries. A sinister presence from the past attempts to capitalize on the havoc created by the alien invasion to destroy the fragile peace between the Parvac Empire and the Galaxic Expanse.
In a deadly game of subterfuge spanning the universes, Teagan and those who are loyal to her may have met their match.