Elizabeth Daly 
Deadly Nightshade [EPUB ebook] 

With war looming, Henry Gamadge is back in Maine, assisting Detective Mitchell on a new cast involving several young children, who have been poisoned with deadly nightshade. Mitchell is stumped and can find no links between the kids, beyond their being about the same age and from the same small community. Could the Gypsies, who are camped nearby, be responsible? And then there is the death of a state trooper at almost the same time…can this be a coincidence? Gamadge and Mitchell must connect the cases and solve the crime in this classic Golden Age mystery.