The first three volumes of the Mercenaries series are a trilogy not only because of their number but because the story is a continuous tale. This book, Part Four, is a stand-alone volume. Events occur in a region barely mentioned in the trilogy and the story is complete. Many characters are new; many old characters are not present.
MERCENARIES: Vol. I: Storm Approaching
Vol. II: Gold and Glory
Vol. III: Resolution
Vol. IV: The Free Lands