Life for a family on a Nebraska homestead is difficult, with illness and weather causing worries about crops and finances, and conflicts between ranchers and farmers. For 11-year-old Nate's family, the days grow even darker when he gets his leg crushed in a farm accident. To help out, Nate's father brings home John Worth, just off the Orphan Train and dealing with the loss of his own family in a New York City tenement fire.
Under a Dark Summer Sky is set in Florida in 1935 in a small town struggling with the effects of the Depression and at the time of the great hurricane. The racially charged narrative swirls around Missy, with her courageous dedication to duty, who works for the Kincaid family; Henry, a long absent WWI soldier who still loves Missy, the girl he left behind; Henry's sister and Missy's friend, Selma, with her no-nonsense approach to crises; and Sheriff Dwayne Campbell, whose duty is to protect Henry but who has personal reasons for wanting Henry to suffer.
Florida, 1935, and the residents of Heron Key are preparing for the Fourth of July barbecue, little realising how much their world is about to change. Domestic helps Missy and Selma are dismembering the alligator that tried to snatch the baby Missy was watching, before they can get ready for the party. Henry, a returned soldier from WW1, is hoping that his comrades in his construction team will not disgrace themselves in front of an already fiercely judgemental community.
Kyna has a deep-seated (and well-earned) fear of the water. So when her adoptive parents announce that they have rented a summer house on Lake Champlain, she begs to be left behind for the summer. Alas, this is not possible. Yet even at the lake Kyna does her best to avoid the water. But when her new friend, Tylo, draws her into his quest for strange water creatures, Kyna finds herself pulled into unexpected discoveries.