Murder my Neighbor by Veronica Heley

Ellie Quicke is confronted by an angry young man, demanding to know what has happened to his elderly great aunt. Flavia Osborne had refused to move in with her relatives, telling everyone that she'd sold her secluded house and was moving to a retirement flat - but it seems she never arrived at her destination. Ellie is distracted by her difficult daughter Diana, who makes a shocking announcement, but Russ insists Ellie help him discover the truth. Where is Flavia, and who knows more than they are prepared to tell?