Father Brown knows the Pope's coronation gift to the Queen of a priceless cross is too tempting to Flambeau and Brown convinces the Bishop to let him guard it. Flambeau arrives on Brown's doorstep seeking his help to steal the cross to save the life of his daughter he has never met; kidnapped by Flambeau's criminal partner he once left for dead. Before they can steal the cross it goes missing from the Bishop's Palace. Brown has underestimated Papal politics, Flambeau's daughter, and the consciences of men.