Dervla McTiernan
For years the boglands of Northern Europe have given up bodies of the long-deceased. Bodies that are thousands of years old, uncannily preserved. Bodies with strange injuries that suggest ritual torture and human sacrifice. When a corpse is found in a bog in Galway, Cormac Reilly assumes the find is historical. But closer examination reveals a more recent story. The dead man is Thaddeus Grey, a local secondary school principal who disappeared two years prior. There's nothing in Grey's past that would explain why he was murdered, or why his body was mutilated in a ritual manner.
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Link
https://darwin.on.worldcat.org/oclc/1472059777