Nighttime Is My Time — Mary Higgins Clark

Historian Jean Sheridan returns to Cornwall-on-Hudson, New York, excited about her twenty-year high-school reunion at Stonecroft Academy. But a dear friend of hers soon becomes the fifth woman in the class to meet a sudden, mysterious end. Then Jean receives a taunting fax about a child she gave up for adoption, whose existence she had kept a secret but whose life may now be in danger. For present at the reunion is The Owl, a murderer on a mission of vengeance against women who once humiliated him...and Jean is his final intended victim.