The CHalice of Blood by Peter Tremayne *****

The Chalice of Blood by Peter Tremayne is a wonderful locked-room murder mystery set in 7th century Ireland. Brother Donnchad is discovered after the abbot had to resort to calling the blacksmith to break down the door. Inside Brother Donnchad is discovered murdered, still in possession of the only key to the lock, the only lock every used in this religious community, recently made by the blacksmith just for Brother Donnchad.

The investigation is lead by Fidelma of Cashel, sister of the King, legal scholar, and famous investigator and prosecutor. This is a woman who is often soft spoken and polite, though never flirtatious or deferent. When it suits her purposes, she can be regal, forceful, and demanding of absolute respect and obedience ... which she never fails to receive.

In addition to a wonderful mystery, Celtic scholar Peter Tremayne (pseudonym) packs the story with details of 7th Ireland: social and legal structures, vocabulary, and, central to the story, the transition from the traditional pagan/druid religions to Christianity.

Overall and excellent mix of mystery and history, or escape and education.

I found jarring one anachronism. These 7th century Celts seem oddly prescient in their references to centimeters, meters, and kilometers which weren't to be appreciated by the rest of Europe for another thousand years, and even longer in parts of the yet to be discovered Americas.