The Last Testament by Sam Bourne

Maggie Costello is a "closer," an expert brought into negotiations when all other options have failed. Now in Jerusalem, she mediates peace talks between Israel and Palestine, which have broken down after two high-profile deaths. Right-wing Zionist Shimon Guttman was gunned down during a supposed attempt to assassinate the Israeli prime minister. "This will change everything," Guttman had cryptically warned the prime minister before he was killed. Palestinian Ahmed Nour, a respected archaeologist, has also been killed on suspicions of being a collaborator. When Maggie discovers that the two men were colleagues, she is plunged into a mystery rooted in an unsolved riddle of the Bible. It all leads back to an ancient clay tablet looted from Baghdad's Museum of Antiquities and a secret that could end a war-or spark a new one.