The scene shifts to the next day when class 5 goes on a school trip. The class dynamics change a lot after the recent monthly vote and the dodgeball fight the day before. After going to the aquarium, everyone goes to the beach. Soo Ji still hasn’t told her friends about how Harim used Soo Ji's dad to threaten her and tells them she might delay uploading the recording. Harim meets Soo Ji in private and asks her how it feels to betray her friends and Harim's goal to break the friendship of Soo Ji's team. Meanwhile, Yerim is mad to learn that Eun Jeong has decided not to compete in the swimming tournament this time; she goes to find Eun Jeong to ask why and if her will involve Harim. It turns out Harim used Yerim's debut to threaten Eun Jeong, and now she intends to use Eun Jeong to threaten Yerim to betray Soo Ji. Not only that, but she also meets with Jae Hyeong and uses her brother to threaten her. Jae Hyeong's brother is attending a job interview today at a law firm, and the interviewer used to be the legal consultant for Baekyeon Corporation. Harim wants to use her power to make all the people around Soo Ji betray her. While the girls go to dive, Harim is pushed by someone and falls into the diving pool. Harim is very good at bullying but doesn’t know how to swim and starts to drown. Ja Eun instantly jumps in to try to save her, then Eun Jeong and the lifeguard also jump in to help them. Harim is fine, but Eun Jeong's leg is hurt after that. However, when Mr. Lim finds out, he only cares about Harim and shouts at everyone else. He wants to bring her to the hospital, but Harim doesn’t want to go and steps on his feet, telling him to shut up. Do Ah saw Woo Yi was the person who pushed Harim and tells her not to act on something she can’t control. Woo Yi freaks out and tries to deny it, but then admits she didn't intend to do so and that no one else cared about Harim, except Ja Eun, who was the only one to jump in to help her. Meanwhile, the rich girls' dads are having sushi together. Do Ah's dad mentions the pyramid game and thinks they should tell their daughters to stop because it has become too violent and serious, involving also them as the parents. In the evening, the girls are transported to their accommodation and they are asked to divide into five groups. Soo Ji's group sticks together, and Yurim joins them, while Harim signals for Eun Jeong to join her group. Yurim turns out to be the friend who betrayed Ja Eun, leaving her in rank F. At night, Harim texts Yerim and Jae Hyeong, telling them they will have to follow her orders. Later, Yerim and Jae Hyeong surprise Soo Ji with a cake for her birthday. They all have fun, and Yerim posts their pictures on Instagram. Woo Ri sees the pictures and comments, "Looks like you are having fun." Meanwhile, Woo Ri is still haunted by the nightmare she had in class 5. Seung Hwa texts her, promising to help her get rid of all these bad memories. Woo Yi meets Harim and asks her why she didn’t do anything even after realizing Woo Yi was the person who pushed her. Harim says that someone else has angered her more, and to her, Woo Yi is no one. Ja Eun suddenly receives a phone call from her mom. Harim has Ja Eun's mom brought to the accommodation to meet her. Ja Eun's mom is happy to see her and brings her some strawberries, but Ja Eun, for some reason, is scared and looks at Harim. Harim tells Ja Eun's mom that they should meet more often, which terrifies Ja Eun even more. After Ja Eun's mom leaves, Harim stamps on the strawberries and repeats what Ja Eun's mom says, that So Woon (the name Harim uses with them) is Ja Eun's best friend. She threatens to expose Ja Eun's secret and also reveals that Soo Ji has betrayed them to protect her dad. The next day, the class participates in a paintball game. Eun Byeol states that the person who gets more than three shots will be eliminated and have to go to the final to choose one as rank F. Yerim tries to meet Eun Jeong to talk about her swimming career, however, they both get shot, and when Eun Jeong sees that Yerim already has 2 shots, she shields Yerim and takes the shot herself. Woo Yi ends up attacking Soo Ji and accuses her of ruining everything since she transferred there. Soo Ji fights back and manages to get her gun and starts shooting at Woo Yi. She keeps crying, and Soo Ji asks her to stop acting like a victim. Meanwhile, Harim finds Ja Eun, and Ja Eun stays still to let Harim shoot her three times in a row. The game ends with Soo Ji, Ja Eun, Jae Hyeong, Eun Jeong, and Ji Ae getting shot the most. Eun Byeol asks them to shoot each other while telling one bad quality of the person they are shooting. The game stops when everyone runs out of bullets, and the one who gets shot the most will be the rank F student. Yerim, Jae-hyeong, and Soo-ji receive a message from Ha-rim asking them all to betray their friends. Harim tries to break their friendship, and eventually, Ja-eun is left alone like before. However, Ji-ae suddenly points the gun at herself and keeps shooting while calling herself a traitor. A flashback from the night before shows Soo-ji, Ja-eun, Jae-hyeong, and Ye-rim meeting outside and telling the truth about Ha-rim trying to blackmail them. Jae-hyeong tells her friends that she did not care about her brother losing his career as he always beat her to the point that she had to get eye surgery. Yerim also claims that Eun-jeong is no longer a friend to her because she doesn’t prioritize her career. They also tell Ja-eun to stop blaming herself because everything was Harim's fault. A flashback also shows that Soo-ji didn’t delete the voice recording. In the present, all of the girls point the gun at themselves, and Soo-ji stares at Harim.