During a Little League Baseball game in the quaint town of Millbrook, New York, the Abbott family—comprising Evelyn Abbott and Lee Abbott, along with their deaf daughter Regan Abbott and sons Marcus Abbott and Beau—find themselves in the midst of a terrifying event. They witness a strange, meteor-like object plummet towards the Earth. Shortly after its arrival, deadly extraterrestrial entities known as the Death Angels emerge, wreaking havoc and slaughtering the unsuspecting townsfolk. These blind yet terrifying creatures are equipped with armored skin and possess extraordinary speed and strength, hunting their victims via their acute sense of hearing, targeting anything that produces even the faintest sound.
Fast forward over a year later, the devastating aftermath reveals that the Angels have decimated a significant portion of the world's population, tragically claiming the lives of Lee and Beau in the process. Amidst the chaos, Regan has discovered a potential weakness; she learns that high-frequency audio feedback makes the creatures vulnerable. Using her ingenuity, she devises a method to transmit this noise through her cochlear implant with a portable microphone. With their home in ruins, the surviving members of the Abbott family set out on a quest to locate other survivors.
However, things take a perilous turn when Evelyn accidentally triggers a sound alarm in a fenced-off area, alerting the Angels to their presence. During their frantic escape, Marcus unintentionally steps into a bear trap, drawing the attention of one of the Angels with his cries. In an act of desperation, Regan and Evelyn manage to eliminate the Angel, freeing Marcus as they take refuge in an abandoned steel foundry.
They encounter an old friend, Emmett, who takes them to his soundproof underground hideout. Emmett, having recently lost his own family, has developed a grim outlook on life and is initially reluctant to offer further assistance. While at the hideout, Marcus hears the haunting tune "Beyond the Sea" playing on the radio, which Emmett points out has been broadcasting for the last four months. This prompts Regan to theorize that it may hold a clue about survivors hiding out on the Norwalk Islands, a day's journey to the southeast. She resolves to reach the island's radio tower, believing she can broadcast the high-frequency noise from her hearing aid so that other survivors can exploit the signal.
Regan bravely sets out alone on her mission but soon finds herself under attack. Fortunately, Emmett comes to her aid, saving her from the clutches of an Angel. Afterward, she convinces him to assist her in achieving her goal. Meanwhile, Evelyn is faced with the responsibility of leaving her newborn baby with Marcus at the foundry while she goes into town to procure medical supplies. In a turn of events, Marcus stumbles upon the remains of Emmett's wife, inadvertently attracting the attention of an Angel. In the ensuing chaos, he accidentally locks himself and the baby in an air-tight compartment, heightening the tension.
As Emmett and Regan reach a marina to board a boat to the island, they are ambushed by a group of deranged bandits. In a calculated move, Emmett draws the attention of the Angels, leading to the bandits’ demise at the hands of the creatures. It becomes evident that the Angels are unable to swim when one of them drowns during the scuffle. The duo rows to the island, discovering a small colony of survivors living relatively normal lives. The leader of the colony reveals that the U.S. government had attempted to rescue people by moving them to the islands, but the chaos of boarding created noise that attracted the Angels, resulting in a disastrous outcome where only two boats out of the original twelve made it to safety.
Back at the foundry, Evelyn manages to free her children just in time to avert suffocation. They find refuge inside a bunker as an Angel prowls nearby. The following day on the island, an Angel that has drifted ashore launches an attack on the colonists, claiming the life of the colony leader. In a crucial moment at the radio station, Regan successfully transmits the high-frequency signal, incapacitating the Angel before striking it down with a metal conduit.
Simultaneously at the foundry, Marcus hears Regan's crucial transmission and uses a portable radio to broadcast the same high-pitched frequency he received. This enables him to eliminate the Angel in their midst. In a final gesture of hope, Regan leaves her hearing aid connected to the radio station's microphone, allowing the potent broadcast signal to be weaponized by future survivors, empowering them to fight back against the lurking threat.
