Teetotaled / Maia Chance.

Enhanced descriptions from Syndetics:

After her philandering husband died and left her penniless in Prohibition-era New York, Lola Woodby escaped with her Swedish cook to the only place she could--her deceased husband's secret love nest in the middle of Manhattan. Her only comforts were chocolate cake, dime store detective novels, and the occasional highball (okay, maybe not so occasional). But rent came due and Lola and Berta were forced to accept the first job that came their way, leading them to set up shop as private detectives operating out of Alfie's cramped love nest.

Now Lola and Berta are in danger of losing the business they've barely gotten off the ground--work is sparse and money is running out. So when a society matron offers them a job, they take it--even if it means sneaking into a slimming and exercise facility and consuming only water and health food until they can steal a diary from Grace Whiddle, a resident at the "health farm." But barely a day in, Grace and her diary escape from the facility--and Grace's future mother-in-law is found murdered on the premises. Lola and Berta are promptly fired. But before they can climb into Lola's brown and white Duesenberg Model A and whiz off the health farm property, they find themselves with a new client and a new charge: to solve the murder of Grace's future mother-in-law.

Teetotaled , Maia Chance's sparkling new installment in the Discreet Retrieval Agency Mysteries will delight readers with its clever plotting, larger-than-life characters, and rich 1920s atmosphere.