The Crystal Seas

The Crystal Seas Book 16 in the Richard Blade series.
The Empire of Nurn
In his most challenging adventure, Blade is held captive in a new Dimension by a marauding race of amphibious mermen. But Blade quickly learns that none are so treacherous as the double-dealing Nurnians who conspire to pit the mermen against the floating Sea Cities of Talgar in a lethal struggle to end in mutual annihilation.
Escaping from the mermen with the assistance of a beautiful and influential woman, Blade has learned the bitter truth--the Nurnians will stop at nothing in their insatiable quest for power. But in their blinding lust for dominance of the Crystal Seas, they have become careless.
Blade, disguised as a Talgarian arms buyer, penetrates the Empire and kidnaps one of the leading merchants. The astounding revelation of the Nurnian treachery and their evil deception bonds the mermen and Talgarians together against the Empire. But the new alliance must first survive the all-out attack of the formidable Nurnians, who remain determined at all costs to rule the Crystal Seas.