Mary Russell: She is nineteen, and currently on a break from studying theology at Oxford University. During the escapade, she is dressed as a young Bedouin man and must learn the Arabic language on the go. She keeps throwing knives in her boots and has excellent aim.
Sherlock Holmes: The aging detective has recently had his back badly hurt in The Beekeeper's Apprentice. He visited Palestine previously, and so already has experience with the customs and language, to a certain degree.
Mahmoud Hazr: He works as a traveling scribe, which covers up that he and Ali are British spies. He has a scar on his face from being previously tortured. He is taciturn and is described as being as steady as a rock.
Ali Hazr-: He is Mahmoud's younger brother, and dresses very flamboyantly. He uses a large unwieldy knife for everything, including carving small wooden figures. He has excellent night vision, and is said to have, “Eyes like a cat.” He is highly distrustful of Holmes and Russell when they first come.
Joshua: He is a spymaster, whom the Hazrs report to. He collects reports from a small shack outside of Beersheva. He was in France fighting in the trenches for six months during World War I and works for the British Empire.