Murder at Feathers & Flair — Lee Strauss

It's 1924, and war-widow fashionista Ginger Gold s new Regent Street dress shop, Feathers & Flair, is the talk of the London fashion district, attracting aristocrats from Paris to Berlin to Moscow. 

Ginger is offered her first job as a private detective when her sister-in-law's stage-actor friend goes missing, and though the dress shop takes most of her time, Ginger takes the case. But when a Russian grand duchess dies at the shop's official grand-opening event, Ginger ignores the missing person to chase a killer. It's a decision she will live to regret.