Sunken Empire

Some treasures are meant to stay buried. So are some secrets. Callum Tremaine has spent six years running from the family name that made him - disowned heir, fugitive art thief, the only Tremaine with a conscience and a target on his back. Now he's holding a five-hundred-year-old Moorish map to seventeen lost vaults scattered beneath the Mediterranean, each one packed with stolen gold and the documents that could put his family behind bars forever.
The last thing he needs is the FBI agent sworn to bring him in. Special Agent Maddox Langley followed the rules his entire career. Followed them right up until he watched the Bureau he trusted turn into the weapon hunting them both. Now his badge is gone, his loyalties are wrecked, and the only thing his every instinct insists on protecting is the infuriating, brilliant man he's supposed to arrest.
From a sweltering safehouse in Seville to the flooded cisterns beneath Istanbul, Callum and Maddox are chasing a fortune that men will kill for - pursued by Callum's ruthless family and the untouchable broker who owns the city. With every vault they crack, the walls close tighter, the water rises higher, and the thing building between them gets harder to call professional. They came for the empire under the water.
Staying alive long enough to claim it - and each other - may cost them everything.