Emmett attends his son's baseball game in Millbrook's park along with Lee and Regan. Emmett shouts out for one of the kids to dive for the plate and asks Regan how to say "dive" in ASL. Suddenly, an unidentifiable object comes hurtling towards the town and the game ends abruptly. On his way home, he sees Lee, who asks if his brother has said if anything is going on at the base, but Emmett isn't sure. However, he assures to notify Lee if anything comes up.
Emmett is held up at a rail yard when one of his booby traps is tripped. He spots Evelyn, Regan, and Marcus running through the field. However, Marcus then gets caught in a bear trap. He screams and attracts a creature. After witnessing Regan and Evelyn kill the creature, Emmett helps them inside and hides them inside a steel, soundproof bunker. He tells Evelyn and the kids that they can't stay, as there aren't enough supplies. She asks to see his face, realizing that the man is Emmett. Hoping to appeal to him, she shows him the baby inside the box. The timer then goes off, and Emmett opens the door to exit the bunker. In that time, it seems the creature has left.
Emmett tells Evelyn that it's safe to talk, as they're under three feet of concrete. He inquires about feedback from the microphone and how it seems to irritate the creatures, but Evelyn doesn't exactly know the science behind it. Evelyn gives her condolences, assuming that Emmett's family is dead. He reveals his kids died the first day and that his wife, Nora, died just 11 weeks ago from an illness. Evelyn then asks Emmett if he knew it was Lee when he saw the flame night after night. Emmett admits that he knew, but he didn't consider coming for them because people have changed since it all began.
The radio starts playing "Beyond the Sea". Emmett has been hearing it as well. It's been playing on repeat for the last four months. Regan wonders why they never heard it before. Emmett explains that it can only be heard from the valley. Regan is convinced that it's a message from someone for them to travel across the sea. However, Emmett tells them that there is nothing left and that the song isn't a message or signal of any kind.
The following day, Emmett learns that Regan has left on her own to cross the sea as the song said and goes after her at Evelyn's behest. Emmett tracks Regan down to a stalled train, where she is nearly killed by a creature. He gets there just in time to kill it and rescue Regan. The two of them race back to the station and take cover, as the gunshot has alerted the other creatures. Emmett tries to convince her to come back with him, but she refuses. Instead, she convinces him to join her on her journey across the sea.
Emmett and Regan arrive at the Marina, where they come across a little girl, who is seemingly alone. She is crouched down on the deck and cowering. Emmett cautiously approaches, and the little girl ties a noose around his neck. The little girl is then joined by a group of scroungy-looking men, who have taken an interest in Regan, ripping off her shirt and removing her implant. As they take her back to the ship, Emmett recalls her telling him how to say "dive" in ASL and instructs her to jump in the water. With Regan out of harm's way, Emmett attacks one of the men with the net connected to the rope that's wrapped around his neck. He uses the net to hold the man in place long enough for the creature to attack. Emmett then jumps into the water, where he struggles for a moment to get the rope from around his neck. One of the creatures notices Emmett in the water and dives for him but ends up drowning. The other creature watches helplessly from the ship. Regan then comes through in a boat and pulls Emmett out of the water. He opens his mouth and reveals to Regan that he has her implant.
The two of them cross the sea to an island, where they find a community of people who are seemingly untouched by the creatures. They are greeted by an island man, who presumes that they heard the song over the radio and figured it out, but Emmett admits that it was solely Regan who figured it out. Emmett reveals that it took them just under two days to make it to the island. Emmett then finds Regan and returns her implant. He also apologizes for ever doubting Regan. Emmett then heads to the beach and unfolds the drawing of his wife from his pocket. While on the beach, he hears a loud crashing sound and follows it to the edge of the shore, where he finds the very same boat he saw the creature hanging onto when they fled the Marina.
Emmett rushes back to the community to warn them, but he is too late. The creature has already begun attacking people. On his way inside, Emmett grabs a random child from the field and brings him inside, and hides him in a closet with another child. Regan, Emmett, and the island man get in a car and draw the creature away. The island man is killed once they reach the station.
Emmett and Regan creep through the radio station so as not to be heard by the creature. Regan makes her way over the counter and into the main office, where the equipment is located. However, when the door creeks, the creature comes rushing towards them and slashes at Emmett's leg. Regan turns on the broadcast signal and matched with her hearing aid, it creates a high-pitched frequency that is transmitted both towards the creature in front her of as well as all the radios within a distance of the broadcast. Regan then takes a lead pipe and crushes the creature over the head.
- The only sign language that Emmett knows is "dive", which was shown to be useful near the end of Part II. It was originally taught to him by Regan during Marcus' baseball game (aka Day 1).