Scotland Yard Inspector Ian Rutledge
is assigned one of the most baffling investigations of his career: an unsolved
murder case with an unidentified victim and a cold trail with few clues to
follow 

A woman has been murdered at the foot of a megalith
shaped like a great shrouded figure. Chief Inspector Brian Leslie, one of the
Yard’s best men, is sent to investigate the site in Avebury, a village set
inside a prehistoric stone circle not far from Stonehenge. In spite of his
efforts, Leslie is not able to identify her, much less discover how she got to
Avebury—or why she died there. Her killer has simply left no trace. 

Several weeks later, when Ian Rutledge has returned from successfully
concluding a similar case with an unidentified victim, he is asked to take a
second look at Leslie’s inquiry. But Rutledge suspects Chief Superintendent Markham
simply wants him to fail.

Leslie was right—Avebury refuses to yield its secrets. But Rutledge
slowly widens his search, until he discovers an unexplained clue that seems to
point toward an impossible solution. If he pursues it and he is wrong, he will
draw the wrath of the Yard down on his head. But even if he is right, he can’t
be certain what he can prove, and that will play right into Markham’s game. The
easy answer is to let the first verdict stand: Person or persons unknown. But
what about the victim? What does Rutledge owe this tragic young woman? Where
must his loyalty lie?