A Guilty Thing Surprised — Ruth Rendell

EVERYONE LOVED ELIZABETH
--including one man who had no right to. For it was clear that the glamorous mistress of Myfleet Manor had slipped away from her husband to meet a secret lover-and had met her death instead.

Was her lover the killer? Or was he the cause? Either way, he had to be found--and with alibis crumbling before their eyes, motives multiplying and scandal erupting, Chief Inspecter Wexford and his straitlaced assistant, Burden, pressed the search for him.
And when they found him, they wished they hadn't...