Undercover - Federation Chronicles, #1

An erotic future universe of passion, danger, and deceit... On the battleground or in the bedroom, one woman and two men fight for dominance in a bold, new, and excitingly different direction in erotic romance... As a lieutenant of the Federation military, Sera Ayers is accustomed to giving orders, not taking them. Now she must obey the one man she can't stand-and can't stop thinking about. With the enemy Imperialists gaining ground, a covert team is assembled by Ash Walker.
Ten years before, Sera had lovingly submitted to Ash's dominance in the bedroom. But when he was forced into a political marriage, she refused to play mistress. His marriage now over, Ash wants Sera on his team-and back in his bed. The third team member, Brandt Pela, has an elegance to match Ash's savage sexuality. And when their undercover plan requires Sera to pose as Brandt's lover, it ignites a passion among the three of them more dangerous than their mission.