Moonstone. Rogue Moon Series, #3

A priceless moonstone artifact has been stolen and Detective Melissa Cartwright is charged with recovering it. But when that artifact is found to have deep ties to the evil Lycan Syndicate, Melissa knows there's only one person she can turn to for help. The most notorious rogue werewolf in the city - and her secret love. Billionaire werewolf, Trevor Dare, has no loyalty to the Syndicate that keeps trying to dictate how he lives his life, governs his pack, and loves his woman.
And when they make a move to start a war between the factions, Trevor knows he must do all he can to keep the peace. At least until he discovers the Syndicate's true motives. The moonstone the lycans call the Enchanted Moonbeam is at the heart of the conflict. And when the fighting breaks out, and Melissa's humanity is threatened, Trevor will forge an unlikely alliance to hold the packs together. As the threat of war builds, keeping Melissa safe and human will become a game for fools.