In Palestine Mary and Sherlock meet up with Mahmoud and Ali Hazr, two apparently Bedouin guides, to counter a plot against the British in Jerusalem under General Edmund Allenby.

Mary Russell: She is nineteen, and currently on a break from studying theology at Oxford University.

Sherlock Holmes: The aging detective has recently had his back badly hurt in The Beekeeper's Apprentice.

Mahmoud Hazr: He works as a traveling scribe, which covers up that he and Ali are British spies.

He was in France fighting in the trenches for six months during World War I and works for the British Empire.