The episode opens from where the second episode left off. To ease the tension between her brother and Rem, Ritsuka introduces Lindo to Rem. Rem approaches him and introduces himself. He extends his hand to him, but Lindo ignores the gesture. Instead, he grabs Ritsuka's hand and starts walking away with her, telling her that they're going home. As Ritsuka is being pulled by her brother, she quickly thanks Rem for today. The next morning, Rem storms into the 'Third Library' in a foul mood. As he takes his seat at his desk, Mage asks him if he got up on the wrong side of the bed. Urie asks Rem if he wasn't able to find the "grimoire" in Nagano which only makes him irritated. Shiki sighs that he wished to have seen the house burn down, saying that it must've been beautiful. Mage slams his feet on the table telling Rem that he should've stolen it before someone else got their hands on it. Urie approaches Rem from behind and tells him that if he finds it too troublesome, then he might do a better job than him. He reaches out to move one of Rem's shōgi pieces on his board, but Rem stops him. He firmly tells Urie to not act out of turn.

Meanwhile, in the Tachibana house, Ritsuka is fast asleep in bed when the curtains of her room are drawn open. The sunlight awakes her and she turns around to find Lindo wearing an apron which startles her. He tells her to get up and Ritsuka sternly tells him that he shouldn't barge into a young lady's room like that. Lindo retaliates by asking her if a young lady sleeps like how she was earlier on. This makes Ritsuka embarrassed and she asks Lindo if he saw her like that, but Lindo tells her she should hurry up and change, telling her that her breakfast will get cold. He leaves her room and just before he closes her door, he smirks and Ritsuka calls him infuriating. The scene then changes to their dining room where Lindo has laid out a breakfast feast for his sister. Ritsuka compliments Lindo's cooking skills as she sits down to eat and Lindo tells her to change out of her school uniform once she's done eating. When Ritsuka asks why he only tells her to take a break from school for a while. This startles and confuses her and Lindo reminds her that he had told her to stay away from Rem. Ritsuka asks why, because she wants to apologize to Rem on his behalf for the way he acted towards him the previous night.

Lindo suddenly sprinkles water around the dining room and when Ritsuka asks what it was, he tells her that the water is 'holy water' from Fatima. Ritsuka then asks what he is doing with it, but Lindo ignores her question as he continues sprinkling the 'holy water' around the house. As he goes outside, he instructs her to stay inside. Curious, Ritsuka follows him out onto the porch where she sees her brother clutching his rosario while murmuring some words she couldn't quite catch on. Later that day, Ritsuka is chatting with Azuna on the phone. She tells her about Lindo, but Azuna tells her that it may be better to listen to her brother for now. Azuna suddenly tells her that her mother allowed her to spend the night at her place today and she offers to buy the cream puffs Ritsuka likes. This delights Ritsuka and she tells Azuna she'll see her later and hangs up, just as Lindo enters her room. Ritsuka informs her brother that her best friend will be staying over at their place tonight and Lindo seemingly doesn't mind. He tells her that he'll be heading out for a bit, and he tells Ritsuka to not leave the house no matter what. As Lindo leaves the house, he tells himself that he will definitely protect his sister.

In her room, Ritsuka flops onto her bed and clutches her pendant. She tries to sing 'Premonition of the Wind' ("Kaze no Yokan" 風の予感), but upon remembering the events that happened in the first two episodes, she stops. She rolls over and quietly hopes that Maria will be alright. Her thoughts are interrupted when there is a sound of tires screeching followed by a crash and a scream from outside causing Ritsuka to perk up. She dashes out of the house to investigate, only to find an empty road. She looks around confused until Urie holds out his rose in front of her face which startles her. She exclaims his name and Urie appears delighted that she remembered him. Ritsuka explains that it's because he's quite famous at school and she asks why he is here. Urie explains that she wasn't at school today and it made Rem worried, but Ritsuka says that her brother told not to leave the house today. She then invites him in for tea since he came all the way here, but Urie notices the holy water marks around the property and declines. He suddenly tells her that they have news about her mother and Ritsuka immediately says she'll get ready. She dashes back into the house to get changed and Urie watches her with a sly grin.

Sometime later, Ritsuka is with Urie outside a large building in the school. She asks him if Rem is in there, but Urie ignores her by opening the doors and he tells her to come in. It is the school's conservatory. As they wander about, Ritsuka is amazed at how large it is until she hears some singing. It is not long before they arrive at a terrace where there are students with masks. Urie follows from behind and the female students with masks rush up to greet him. He then takes Ritsuka's hand and seats her down on a couch in the pavilion. Unbeknownst to them, a mysterious boy with blue hair is sitting on the sill of one of the glass panels, watching them from afar. The female students each insert a jealous comment and Ritsuka asks Urie where Rem is. Instead of answering her question, Urie places a finger on her lips and tells Ritsuka that this place is his 'Eden'. He snaps his fingers, leading into his song 'Love Temptation' ("Yūwaku Amor" 誘惑❤︎amor) which hypnotizes Ritsuka. Urie then leans in to kiss her, but Ritsuka's pendant emits a bright light which snaps her out of her trance-like state and Urie jumps back in surprise. Ritsuka slaps Urie across his cheek when she notices that he is on top of her but immediately regrets her actions. She nervously asks him of Rem's whereabouts until she notices the masked female students snickering at her which terrifies her.

Elsewhere, Azuna is at a patisserie shop wondering how many cream puffs she should buy for Ritsuka. She decides to call Ritsuka to find out until she remembers that she had to switch off her phone during class. Azuna checks her phone and is surprised to find a voicemail left from Ritsuka. Ritsuka's voicemail informs her that she has gone to school because the Student Council has found out something about her mother. This shocks Azuna who immediately dashes out of the patisserie shop to make an urgent call. Meanwhile, Ritsuka is running through the conservatory while being chased by the masked female students. She frantically searches for the exit, but the lights go out and she finds herself outside in the dark. Ritsuka hides in an alley until Urie snaps his fingers the lights are back on again, revealing the outside to be an amusement park. Surprised, Ritsuka peers out of her hiding place to glance at her new surroundings and is spotted by the girls. She is forced to run again until she spots a funhouse called 'Mirror House' and she decides to hide in there.

In the 'Third Library' Rem notices that someone has touched his shōgi board and he asks who did it. Mage and Shiki clearly deny having been near it and Rem suddenly realizes something. Meanwhile, Ritsuka is wandering through the 'Mirror House' until she hears the girls again, forcing her to flee. She is then cornered and caught by the girls who attempt to remove her pendant until the lights go out causing them to release her. Urie extends his hand to Ritsuka, telling her to come with him and seeing this as no other way out, she takes his hand, and the two escape. They hide behind a merry-go-round while the girls dash past them. After they are gone, Ritsuka thanks Urie for saving her. She is about to leave, but Urie grabs her around the shoulder and pulls her closer to him. He tells her not to move or otherwise they might find her again. Ritsuka asks him what this place is, but he ignores her question by apologizing for giving her such a frightening experience. He explains that his "butterflies" lose control when he gets involved. Ritsuka once again asks him where Rem is because she didn't tell anyone that she came here today and her brother would get worried if she didn't come back. Urie says those are good questions, causing Ritsuka to realize that he had tricked her. Urie points out that he's not the one who's lying, and he asks her why Lindo chose to study abroad in England. Ritsuka replies that her brother wanted to study folklore, and she suspiciously asks Urie how he knew about Lindo.

Urie replies that he knows a lot of things and he asks her if she would like to know Lindo's secret. Ritsuka protests that Lindo has no secrets, but he only tells her to listen carefully. Urie reveals to Ritsuka that her brother is an 'exorcist'. He further reveals to her that Lindo is studying abroad, but at a special exorcist training school. This shocks Ritsuka who suddenly remembers her brother sprinkling 'holy water' around their house and Urie tells her that he's not the liar, but Ritsuka defends Lindo. Urie then asks her why Lindo kept quiet about it and he suddenly mentions her mother. Ritsuka asks Urie if he knows that there is something she doesn't know about her own mother, but he only tells her to ask Lindo, 'her brother whom she trusts so much'. He then reaches out and strokes her fringe while calling her 'sweet little know-nothing Ritsuka' and he tells her to come closer to him, assuring her that he'll make her feel better. His eyes glow, hypnotizing her again and he leans in closer towards her face. Urie suddenly tells her that she has a sweet fragrance much sweeter than a rose, before asking her about the "grimoire" saying she's the only key left. Ritsuka's pendant glows which infuriates him and he orders her to remove it, as he cannot hold her with her pendant in the way. Still under Urie's spell, Ritsuka nods her head and proceeds to remove her pendant, but she is stopped by Rem. Urie gets startled by Rem's sudden appearance as Rem pulls Ritsuka back onto her feet and into his arms. Ritsuka snaps out of her trance like state as Rem sternly reminds Urie that he had told him not to act out of turn.

He then turns to Ritsuka and he tells her that they're leaving, but Urie insists that they are not done yet. He reminds her that she was eager to find out more about her brother's secret. Rem holds out his hand for her, followed by Urie, but Ritsuka backs away from them and rushes off. Rem exclaims her name for the first time and attempts to pursue her, but Urie stops him. He asks Rem why he just addressed Ritsuka by her name. He reminds Rem that he only uses people around him as chess pieces, but why is it that only Ritsuka has him hot under the collar. Rem responds that he has nothing to do with this, and Urie asks him if he doubts his loyalty. He asks him if he is scared that he'll be the one who will get the "grimoire" first, but Rem tells him that it's enough and leaves. Meanwhile, Ritsuka is running through the dark, frantically searching for the exit until she bumps into Lindo. She tries to tell him about the mysterious amusement park and even tries to point it out to him, only to find out that she is back in the real world. Lindo says she must have been imagining things, telling her that she must be exhausted. He then says he's glad he came to get her and that they're going home. As they leave, Ritsuka suddenly wonders how her brother knew of her whereabouts and she refuses to believe that he is an exorcist. Back in the amusement park, Urie is sitting on top of the ferris wheel humming his song. He tells Ritsuka that she is his only special butterfly as he grabs a butterfly fluttering past him. Urie says she is his and only his forever, and he'll hold her until she breaks. The episode ends here.