"The Dark Secrets of Blue River" is a psychological thriller that intricately explores themes of grief, mystery, sisterhood, and dark legacies within the seemingly peaceful small town of Blue River. The story centers on Hillary Brooks, who embarks on a harrowing quest to uncover the truth behind the suspicious death of her twin sister Harley, revealing a sinister web of conspiracies, ancient pacts, and community secrets that threaten to engulf them all.