When introduced to the concept that DNA defines who we are and forever ties us to our relatives, Summer Davis clings to the idea like a life raft, allowing her to feel connected to her beautiful, aloof mother, who abruptly abandoned the family. Summer's father responds to their loss by descending into mental illness, haunted by a lifelong burning secret and abetted by a series of letters that he writes to make sense of his feelings. As Summer deals with her father's illness, her brother's indifference, and her own relationships from adolescence to adulthood, she begins to question the role of genetics and whether she is powerless to escape her family's legacy of despair. But when she decides to put off a science career in New York City to take care of her great-aunt Stella, bedrock of the family and bastion of country wisdom, irreverent insight, and Sinatra memorabilia, Summer begins to learn that her biography doesn't have to define her-and that her future, like her DNA, belongs to her alone.