In the year 666 A.D., a headless female corpse is found in the drinking well of a remote abbey in southwest Ireland. Clasped in one hand is a crucifix; tied to the other arm is a pagan death symbol. Sister Fidelma -- sister to the king of Muman; a religieuse; and an advocate of the Brehon law courts -- is sent to investigate. En route, she encounters a Gaulish merchant ship under full sail off the Irish coast -- one whose crew and cargo have vanished without a trace. Faced with a tense local situation, Fidelma must discover the identity of the body in the well, find out what happened to the missing crew, and determine how these two bizarre events are connected -- before the peace of the entire kingdom is destroyed.