On a rain-swept hillside, hounds from the local foxhunt discover the body of a well-dressed man. At that exact moment, an anonymous caller reports the same body . . . lying half a mile away.

It's only the first in a series of baffling clues as Ben Cooper and Diane Fry--partners and rivals on the detective force --plunge into a case involving horses, spectacular wealth, and a mysterious "plague village" where a centuries-old outbreak of Black Death has been transformed into a modern tourist attraction.

As the spring rain falls and the body count rises, Cooper and Fry's...