As Carol Wheatley drives her car along a mountain road in Washington State, she inserts an unmarked audio cassette into the tape-player. At first, all that Carol hears is a gentle hiss. But the white noise gradually grows louder. As Carol looks up from the player, she sees snow flakes falling in the headlights. When the flakes strike the windshield, they make an impossibly loud sound. The car skids to a halt, and the flakes continue their descent, cracking the windshield. Carol jumps out of the car, only to find herself standing on ice. Beneath the surface is the face of a drowning boy, his eyes bulging in desperation. Carol climbs back into the car and throws the engine in reverse. The car backs out onto the roadway, where it is smashed by an eighteen-wheel truck.
At Quantico, Frank finds an internal envelope containing an audio cassette mixed in with his other mail. He slips the cassette into a boom box and hears the same white noise. Suddenly, he experiences an internal vision: a face under the ice. Frank looks at the internal envelope, and sees that the last name written on it (above his own), is a "Victor Chyren." A check with the operator reveals no such person working at the FBI. Frank then notes the name written above Chyren: Doug Scaife. Scaife, who never heard of Chryen, tells Frank that Giebelhouse sent him the tape for analysis. Nothing could be found on the cassette, except for white noise. Frank listens to the tape and experiences a vision of Catherine standing on the porch of the yellow house. He notices a wave pattern that Scaife identifies as pink noise. Frank concludes that someone intentionally made the tape.
Frank travels to Washington, where he and Giebelhouse review the accident scene. He then interviews the victim's mother, Mrs. Wheatley. Frank correctly deduces that, at some time, there had been an accident, one in which a boy fell through the ice and drowned. Deeply shocked, Mrs. Wheatley confirms this is so. Her daughter had always blamed herself for the accident. Afterward, Frank tells Geibelhouse that the tape is somehow responsible for Carol's death. He also believes there are more tapes in existence. Meanwhile, a designer named Jerry Origo receives a cassette tape in the mail. He places the tape in his player and listens. A hiss fills the room. Suddenly, flames rip through his penthouse apartment.
Geibelhouse and Frank learn that Origo jumped through a window and fell to his death. They travel to his penthouse, where there is no sign of fire. Geibelhouse finds the cassette tape and the envelope it arrived in, on which is a hand-written address. The envelope bears a Seattle postmark, one Geibelhouse hopes to trace. Frank believes that Origo jumped through the window because he thought he was on fire. He also suspects that someone in Origo's life died in a blaze. It turns out that Origo once worked as a building supervisor on a housing project in New Orleans. A blaze erupted, and because smoke alarm batteries were never installed, seven people died. Origo was investigated but never charged. Frank concludes that when people listen to the mysterious tapes, they hear the things they fear most and suffer massive hallucinations. With that, Frank hands the cassette to Geibelhouse and walks off. He drives to the yellow house, where he experiences another vision of Catherine. When Frank snaps out of his vision, he realizes that the house is now white, and is occupied by a successful contractor named Jeff King. King tells Frank he still gets his mail. He hands him some letters amongst which is an envelope containing a cassette.
As Frank drives, he listens to the cassette tape. He experiences flashbacks in which Watts tells him about the virus, the vaccine, and how only enough exists to inoculate Group members. He makes his way to the remote cabin where he had brought Catherine and Jordan in hopes of escaping the outbreak. Meanwhile, Emma and Geibelhouse pinpoint the source of the mysterious cassettes: a tape duplicating studio. There they speak with Alice Severin, who identifies the handwriting on the envelope as her own. During the ensuing interrogation, Alice speaks of a ferryman. Moments later, Giebelhouse discovers a notebook containing hundreds of addresses.
Inside the cabin, Frank experiences more flashbacks, reliving the night that Catherine began hemorrhaging from the virus. Frank follows Catherine into the woods, stumbling through the mud. He loses his footing and tumbles, hitting his head on a rock. Meanwhile, Emma and Geibelhouse make their way to the cabin, where they discover the envelope inside Frank's car. Emma correctly deduces that Frank has gone off to find his wife.
Frank opens his eyes and sees Catherine kneeling above him. He laments not having joined the Group, for if he had done so, she would still be alive. Riddled with guilt, Frank believes he let his wife die by letting her walk off into the woods alone. But Catherine reminds him that they were together when she died.
Emma and Geibelhouse find Frank, unconscious but alive. Frank recovers from his ordeal. Later, at Quantico, Emma performs some research. She discovers that the ferryman Alice mentioned is from classical mythology and his name is Charon (like "Chyren"). She finds a reference in Nostradamus which Frank links to the Millennium Group. Alice, he believes, is not part of the Group, but does possess a power. He believes the Group sent him the tape. Though he is unsure of their intention, he is certain of one thing: they gave him back Catherine.