However, fate intervenes, and they reunite with their old friends, Ali Hazr and his brother, Mahmoud, now released from their disguise and known as Alistair and Marsh (characters from the previous book O Jerusalem).

Mary Russell and husband Sherlock Holmes receive a surprise visitor late at night: a much-changed Ali Hazr, one of their Palestinian companions during the events of O Jerusalem (novel) five years ago.

After the death of his older brother Henry, Mahmoud (now Marsh) is determined to do his duty as the new duke, remaining in England and abandoning his nomadic life in Palestine.

To free Marsh from Justice Hall, Russell and Holmes investigate the line of succession, focusing on the former heir Gabriel, Henry’s son, who was executed during the war.

Russell and Holmes then follow Thomas and his mother back to Lyons, and discover that Sidney Darling had coached them to ensure continued control over the estate.

Meanwhile, Russell and Iris sail across the Atlantic to Toronto, Canada to find the green-eyed VAD driver, who turns out to be Philippa Helen O’Meary, Gabriel’s lawfully wedded wife, and the mother of their five-year-old son Gabe.

In the epilogue, Russell notes that Ivo Hughenfort, while awaiting trial, accidentally drowns in Justice Pond, and no foul play is suspected.