Shadows on the Water — Dorothy Fletcher

DARKNESS LURKED IN THE CITY OF LIGHT

Sun refracting on shimmering water like broken mirrors...gondoliers gliding on attenuated poles...Venice was a city of love and light. No wonder Lucy's cousin Diane had been dazzled -- had stayed and married an Italian nobleman.

But when Lucy came to visit Diane and the del Castagno family in their immense palazzo, she discovered Diane had acquired not only a title but a host of relatives to support -- relatives who resented Lucy's intrusion.

Somehow the del Castagnos had a hold over Diane -- something that was making her grow older and thinner with each day. Diane was almost -- decaying...and Lucy was determined to find out why -- before the same thing happened to her...