In the forbidding valley of ancient Ireland, Sister Fidelma must uncover the truth behind a gruesome ritual killing to prevent a war.
In Valley of the Shadow, the 6th century Irish sleuth Sister Fidelma is dispatched by her brother, King Colgu of Muman, to the remote Gleann Geis valley. Her mission: to negotiate with the chieftain Laisre for permission to establish a Christian church and school in his fiercely pagan territory. But upon approaching the valley, Fidelma and her companion Brother Eadulf stumble across a chilling sight - the bodies of thirty-three slain young men arranged in a pagan ritual circle.
As an emissary of the king and a dalaigh of the Brehon courts, it falls to Fidelma to investigate the grisly murders. With the fragile peace of her brother's kingdom at stake, she must unravel the mystery behind the killings at grave personal risk. Venturing into the forbidden valley, this intrepid nun sleuth embarks on her most challenging and dangerous case yet in this authentic and suspenseful Celtic mystery set in 7th century Ireland.