The plot follows a fisherman who encounters horrors and dark truths when an ominous force off the coast of Block Island begins killing wildlife.

Harry's sister Audry who lives on the Rhode Island mainland is sent from her job at the Environmental Protection Agency to investigate the strange wildlife occurrences along with her coworker Paul.

His mental health deteriorates as his other estranged sister Jen returns home to Block Island from New York for the funeral, during which Harry gets in a fight with an older man.

He borrows scuba equipment to investigate the area where Tom drowned, but becomes unconscious underwater only to awaken on the fishing vessel while the electronics are scrambled and a strange noise is emitted.

Harry hits a deer while distracted by a vision of Tom after dropping Jen off at the ferry, and his increasingly erratic behavior spurs Audry to bring him to a psychologist.

The psychologist speculates that he may be suffering from electromagnetic hypersensitivity caused by the Block Island Wind Farm and encourages Harry and Audry to contact a former patient with similar experiences.

The movie ends with Audry being dropped into the ocean alive and treading water as a voiceover plays from an earlier scene where she describes to Emily why biologists justify taking certain individual fish out of their natural habitat to study them.

[7] J Hurtado of Screen Anarchy gave the film a positive review and wrote, "If you're expecting a monster movie, you might be disappointed at the lack of blood and guts, but if you'll open your mind, The Block Island Sound just might scare the hell out of you.