Birds of a feather by Jacqueline Winspear.

Maisie Dobbs has moved into her new office and has a full-time assistant, Billy Beale.  Her latest assignment is to find the run-away daughter of a wealthy grocery chain owner.  In the course of her investigation, Maisie discovers that three of the daughter's friends have recently died.  Coincidence?  Maisie doesn't think so.  She digs deeper to find that during the war the women all participated in the shameful practice of giving white feathers to men who were not serving in the military.  Is someone killing the women for revenge? 336 pages.