Another Way to Kill by Brian Drake

Monaco was a nice vacation–until Steve Dane and Nina Talikova witness a secret agent’s murder.They are now loose ends in a Russian conspiracy to steal a direct-energy weapon from the U.S., but the assassins pursuing them have made a grave miscalculation. Dane and Nina are former spies who know all the tricks and invented a few themselves. Their trail of vengeance leads from Monaco to Texas to a showdown in the Gulf of Mexico, where Dane is taken prisoner by an opponent who intends to settle old hatreds long thought buried.Outgunned and alone, Steve Dane doesn’t soft-sell his brand of payback. He negotiates the only terms the enemy understands: certain death.