"Castle" Season 6 Episode 15, "Smells Like Teen Spirit," opens with two friends watching the video call of their friend, Madison Beaumont, in a cab. To their horror, they soon see Madison's body flying-up, horizontally -- no one is present in the room -- and dropping-down on the floor, lifeless. Castle and Beckett realise that they do not have their song and before they could discuss and agree on their song, they receive a call. It is for the murder investigation of Madison.
At Madison's room, Beckett and Castle discover that Madison's head hit the roof rafter, as her body was thrown against the ceiling. Castle comes-up with the theory of Hulk. Beckett is in love with the kidult, but not in love with his bizarre theories. This murder takes Castle and Beckett to one of Castle's many alma-maters. Castle was expelled from this school because of a cow. At the Fair-Craft Preparatory Academy, Castle meets his old school Principal. The principal does not look too pleased seeing Castle, again, and insists on calls him Mr Rogers.
The Principal shows Castle and Beckett a clip of something that happened in the school cafeteria. It involved a girl called Jordan and Madison and her two friends. Madison and her friends had bullied Jordan and after that flying chairs and tables had attacked them. The video clip suggests that Jordan had used her telekinesis powers to move tables and chair. Castle calls Jordan the real-life Carrie. Before Castle and Beckett can question Jordan, she disappears from school. The two meet Jordan's friend Lucas who is busy doing preparations for the upcoming prom. Lucas tells them that Jordan is not the kind of person to retaliate.
Castle and Beckett find that Jordan got interested in everything telekinesis related after the incident in the cafeteria. They find Jordan at a set-up that demonstrates and teaches harnessing telekinetic powers. Jordan reveals to Castle and Beckett that she is not sure whether she killed Madison, or not. Also, Madison had become mean to Jordan after she had bumped into Madison at the library's Russian section. However, Jordan's alibi checks out.
Ryan and Esposito dig-out the financial details of Madison, and find that she had been on a spending spree and that she had her own secret bank account. The morning Jordan had met Madison at the school library, the latter had stayed out all night and then had gone to the library. Castle and Beckett visit the library, and there in a book they find nearly 2.3 million in bearer bonds, which were issued by the German Government. These bonds were stolen from a bank and a Chinese man, Chen, was caught for this armed robbery. Chen was never indicted and his defence attorney was Madison's father. Beckett and her team are unable to question Chen, as he has gone back to China. His real-estate lady says that Chen's neighbour saw a ghost chasing out Chen, everything was flying in his patio. The superstitious Chinese man and his men left the house and never returned.
The evidence at Chen's house leads Castle and Beckett to Lucas. He had told them that he was not at the school cafeteria when the telekinesis event happened. But, a re-look at the video-clip shows that he is there in the cafeteria at the time. It is Lucas who had made the tables and chairs move, and not Jordan. Lucas confesses that Madison had found out that he was behind the cafeteria's incident. She had blackmailed him, making him do things for her. It included scaring Chen. And, Lucas says that he does not have telekinesis powers but uses magnets and fishing wires to make things move and fly.
To Castle and Beckett, Lucas also confesses that he had helped Madison create a video, using special effects, to scare her friend who was disturbed, because of the cafeteria stunt. This video is same as the call video, but it also has Madison getting-up, smiling and asking Lucas to take the harness off. It is a pre-recorded joke video, and not a face-time call.
The murderer turns out to be one of Madison's friends, Chris. Madison and her friends were into stealing from the families' of co-students. Chris wanted to quit, but Madison would not let her do that, and had threatened to destroy her. Chris had transferred Madison blood to the roof rafter using her skills as the captain of the cheer-leading squad.
Both Castle and Beckett had missed-out on attending their prom, and they join the school's prom. Castle tells Beckett: "Everything I've ever done, every choice I've ever made, every terrible and wonderful thing that's ever happened to me, it's all lead me to right here, this moment with you."
At the prom, the couple also find a song that they both love. It is Andrew Belle's 'In My Veins'.