The Weight of Water is based a novel of the same name by Anita Shreve.
A newspaper photographer, Jeany, travels to the Isles of Shoals with her husband, brother-in-law, and his girlfriend to research the real-life murder of two women in 1873. In a twist of fate, she discovers a storage of papers that appear to give an account of the murders by the lone survivor, a Norwegian immigrant named Maren. The plot weaves between the narrative of these papers and Jean's private struggle with jealousy and suspicion as she suspects her husband of infidelity.