Hearing the phrase ”forensic whodunit in medieval England,” you might think Ariana Franklin’s The Serpent’s Tale will read like ”Er, I fink he got hit in the head wiv a shovel…mystery solved!” But this second outing of Dr. Adelia Aguilar — scholarly Italian expat and gifted coroner — is an impeccably researched tapestry of murder most foul, regal intrigue, and heady feminism. King Henry II’s mistress is dead and Queen Eleanor of Aquitaine is being framed for the deed, so Adelia must clear her name to avert civil war. While Tale gets a bit sluggish in the middle, it’s a refreshing take on a well-worn genre.B+