Peter Tremayne is the fiction pseudonym of a well-known authority on the ancient Celts, who has utilised his knowledge of the Brehon law system and 7th-Century Irish society to create a new concept in detective fiction.

Sister Fidelma returns in THE SHAPESHIFTER'S LAIR, the thirty-first Celtic mystery by Peter Tremayne, acclaimed author of BLOOD IN EDEN, BLOODMOON and PENANCE OF THE DAMNED. If you love Ellis Peters, you'll be gripped by THE SHAPESHIFTER'S LAIR and the Sister Fidelma series.

Ireland. AD 672.

The body of a dead man has been found on a lonely mountain road and taken to the isolated abbey of Gleann Da Loch for a proper burial. The abbot quickly identifies him as Brehon Brocc, who had been travelling to the abbey on a secret mission with Princess Gelgeis and her steward. When news reaches Colgu, King of Muman, that his betrothed, Princess Gelgeis, has disappeared, Fidelma with her trusted companions, Eadulf and Enda, enter the hostile Kingdom of Laigin in search of the truth.

But one death is quickly followed by another and warnings of demonic shapeshifters and evil lurking in the mountains must be taken seriously. Are there really brigands stealing gold and silver from the ancient mines? And are rumours of a war between the Kingdoms of Laigin and Muman to be believed? As Fidelma searches for answers, she must do everything in her power to avoid danger and death in a land where no one is to be trusted...

What readers are saying about the Sister Fidelma series:

'Tremayne is one of those very few historical mystery writers who can perplex and bewilder. He weaves the twisty plots into a complex historical narrative'

'A must-read for anyone looking for a good mystery'

'The characters are original, the settings are imaginative and true-to-life and the intricate plots form enough threads to keep you guessing at every turn'