To Die But Once by Jacqueline Winspear

Die is the latest in the also enjoyable Maisie Dobbs series. This series started around WWI and we're now up to the early days of WWII including Dunkirk and getting ready for a German air attack.

Maisie is asked to consult on the case of a missing young man, the son of the local tavern owner, who had been working as an apprentice and painting military airfield buildings with a flame-retardant paint. He had been complaining about the headaches the paint was causing when he suddenly disappeared. When his body is found, his death is ruled an accident but Maisie thinks there's more to this than meets the eye because she knew the lad--and doesn't think he would have gone out drinking and jumped/fell to his death. And indeed her investigation does open up a whole can of worms. At the same time, she's trying to deal with her assistant Billy's worries about his son in the military as well as her friend Priscilla's sons--and trying to formalize the adoption of her ward, Anna. That's a lot to juggle but as always Maisie is cool and calm throughout.

If you're new to the series, start at the beginning with Maisie Dobbs.