Mystery of the Campagna-Anne Crawford

A swan suffers a mysterious death, its neck wrung by apparent supernatural forces. A young woman dies alone in a hospital room, apparently strangled by mysterious means. Sir Michael Ferrara is found strangled in his bedroom with no one else there. Dr. Bruce Cairn and his son Robert are faced with a mystery that involves deeper, darker, more ancient forces than they could have imagined. Who is Sir Michael's adopted son Antony really? And who is the brood of the Witch Queen? - Summary by Don W. Jenkins