"Falling" is the first episode of Zankyou no Terror.
In Aomori, Japan, a police truck approaches the Nuclear Fuel Reprocessing Facility. Inside the facility, two workers in hazmat suits lodge a heavily shielded spherical shell, named PTS_01, on a forklift. The guards outside the facility see the truck approaching and call the facility's control room. The workers inside carefully take PTS_01 out of a chamber. The driver of the truck outside readies a hand grenade. One of the workers spray-paints "VON" on the floor and looks at the security camera directly above the letters. Outside the facility, the gates begin closing before the truck drivers throws the grenade at them. The explosion triggers the facility's alarm system and the workers go into a state of panic. One of them calmly dislodges PTS_01 and runs with it. The truck breaks into the facility and its driver rushes out from its back with a snowmobile before the security at the facility approach him. The worker reaches a closed gate and threatens the control room via a security camera to shoot the shell he was holding in an attempt to get the gate open. He storms off outside with the security chasing him and finds the snowmobile in front of him. He places PTS_01 in a bag and the two escape the facility in the snowmobile.
Six months after the heist, two boys, Nine and Twelve, walk down the streets of Tokyo in a hot summer afternoon. Nine asks Twelve not to draw attention and blend in with other students. He does not pay much attention to Nine and looks at a bus with kururin. He rushes forward and excitedly sniffs chlorine in the air. At a school's swimming pool, a few girls bully Lisa Mishima into taking a dive. Twelve looks at the situation and realizes the girls were bullying Lisa. They joke on that she herself wanted to take a dip to live the celebrity life in her own "resort". A scared Lisa agrees and says that she was going to take a dip because she was hot. Twelve runs in and jumps into the pool. Lisa describes meeting a smile as warm as sunshine and looking at Nine nearby, a gaze as cold as ice. Nine and Twelve join the school as transfer students under false names of Arata Kokonoe and Tōji Hisami, respectively. Nine helps himself to an empty seat and stares outside the window. Twelve, soaking wet, is assigned the same class as Lisa and the bullies, who make fun of the two.
At the archives section of the Metropolitan Police Department, Mukasa describes the video he was watching to the apathetic Kenjirō Shibazaki playing shōgi. He comes across a peculiar video and shows it to Shibazaki. In the video, two teenage boys wearing masks introduce themselves as "Shpnix". They announce a change in weather forecast for the next day, telling people to expect darkness to descend on Tokyo after 3PM. They predict sparks flying near the Shinjuku area. Mukasa dismisses any credibility of the video and wonders why it popped up at all. A senior worker comes into the room and tells the two to not slack around while on clock. He tells Shibazaki to stop pretending that he was still a detective.
At the school, a few girls approach Nine for his number. He refuses and says that he did not have a cellphone when it pings. Nine gets up and leaves and his cellphone continues to ping. He reaches the staircase and looks at his cellphone and finds several messages by Twelve asking him to come up to the roof where he was drying his clothes. Nine goes to the roof and Twelve greets him. He tells him to stay low and not attract any attention. Twelve retorts that he was not the only one, as he names several girls from Nine's class chat about him. Nine asks Twelve not to remember their names as it was not "normal" for them. Twelve agrees and sees Lisa run to the toilet with her lunch. Nine again reminds him not to get involved. Lisa goes into a stall and sits on the toilet. Her phone buzzes and she finds another one of her other's messages. Disgusted, she hastily stands up, throws her lunch into the toilet and flushes it off.
Three children run up to a security fence with a fire behind them. Two of them grab the fence and begin climbing it and one of them notices the third one fall behind. He repeatedly calls out at her, but she bursts into flames. Nine wakes up horrified and realizes that he was having his nightmare. He drinks some water to calm himself and stands by the window, staring outside. Twelve wakes up and asks Nine whether he had "that dream" again. He tells him that Lisa's eyes were the same as the children from the "institution". Nine says that "they" were weak, which is why they died. He continues that he and Twelve were weak too as they could not save "them", but they had since become strong.The next day at the Tokyo Metropolitan Government Building, Twelve looks at a stand of kururin dolls in a shop. Nine enters the shop and tells him that they had 3 minutes left. He tells him that they would have exactly 26 minutes left before the backup generators flipped back the power on. Lisa runs into the shop and finds Nine and Twelve looking at the dolls. She looks at the two and rushes to the toilet. Her phone buzzes again and she finds more of her mother's messages. Dysphoric, she wishes for everyone to disappear in frustration. A crane rams into a major network of utility poles, severing wires and causing a total blackout in the greater Tokyo prefecture. Mukasa and Shibazaki notice the blackout and Shibazaki remembers the video he saw the day before. He recalls Sphinx's warning about darkness descending on Tokyo. He asks Mukasa to pull up the video. Due to the blackout, people are evacuated out of the Tokyo Metropolitan Government Building. Nine and Twelve begin placing the kururin dolls throughout the building. Lisa exist the toilet and does not notice the evacuation. She finds herself at an emergency exit with Twelve walking down the stairs with a kururin doll in his hand. She calls him out and he is surprised to see her inside the building. Twelve gives Lisa the doll, makes her promise that she will not leave it unless he tells him to and hurries out.
Mukasa and Shibazaki watch the day before's video on a phone. Mukasa calls the blackout a coincidence and Shibazaki ponders about it. 26 minutes later, the lights return. Nine, now outside the building, dials a number on his phone and the dolls start ringing. Twelve comes by his side and Nine asks him if everything went according to their plan. Twelve tells him about Lisa seeing him inside the building. The call triggers the bombs and all of them detonate to mild explosions, triggering the building's alarm system. Water sprinklers put out the fire, but as soon as they turn on, enormous explosions occur. Twelve tells Nine that he left behind Lisa in the building due to her unexpected interference. He tells her that although she would die in the explosions, he left her a kururin for the case she survives. He says that they could either detonate her kururin and kill her right away or save her from an enormous fire. Nine asks whether he was trying to remind him of "that" day. Twelve tells him that helping Lisa might put an end to his nightmares.Twelve calls Lisa and asks whether she was keeping her promise. Nine snatches the phone from him and proposes two options. He tells her that she could either die in the fire or become an accomplice. Scared, Lisa says that she did not want to die. Twelve excitedly runs off and Nine helps her navigate to an exit. He directs her to follow the emergency stairs to the fourth floor. Twelve rushes on his bike to the building. Several explosions occur across the higher levels of the building. The police and the fire department rush to the site of explosions. Nine tells Lisa to put the doll at a specific location and asks her to hide in the hallway. The doll explodes in a connecting corridor. When the smoke sheds, Lisa heads towards the destroyed corridor and finds Twelve just below the building. Twelve opens up his arms and signals Lisa to jump. Lisa remembers her bullies asking her to "fly high" and Nine asking her about her choice earlier. Although terrified, she holds her breath and jumps. The upper portion of the building comes crushing down as she jumps.
At a safer distance, Nine takes a picture of the destroyed Tokyo Metropolitan Government Building and Twelve and Lisa arrive. He looks at Lisa and tells her that she chose to be their accomplice and that she could not turn back. Terrified, Lisa remembers meeting a smile as warm as sunshine and a gaze as cold as ice.