Justin Marquette, a struggling actor, is shot dead in Room 147 of a Best Traveller hotel. At a rehearsal of his theatre company, Beckett and Castle meet Justin's girl friend. She denies that Justin was involved in something illegal, or he was seeing someone else. However, Castle and Beckett come to know that a woman had threatened Justin in front of a coffee. This woman turns out to be Anita Miller.
In 11 seconds, Milles confesses that she killed Justin. Esposito, however, informs Beckett and Castle that Miller was not anywhere close to Justin at the time of murder. There is a solid alibi. Miller insists that she killed Justin and tells Beckett and Castle how she did that, all the details match their theory of how Justin died. Miller, however, cannot recall why she killed Justin and she did not know him, either. She reveals that she had threatened Justin to warn him that he was in danger from her. At the time, Justin was talking to a big, bald man. She mentions about feeling hazy since the last two weeks.
It is confirmed that Justin and Miller did not have a history. At her apartment, Esposito and Ryan find that two weeks of information from her calendar have been erased. Despite Miller's confession, the facts suggest that she did not kill Justin. Castle has no theory to offer to explain the situation. For the first time, he is flummoxed. The case takes another bizarre turn when Sam Carson turns-up, ready to make a confession for the murder of Justin. Carson provides the details similar to Miller. He also did not know Justin, and did not have any motive. Also, Caron felt hazy since the last two weeks. It is soon revealed that he was with his brother at the time of murder. Beckett is completely frustrated when Dwight Carruthers arrives, ready to turn himself in for killing Justin. Castle sees it as an outstanding case.
Beckett and her team are able to identify the big, bald man, with whom Justin was having a talk. The same man, Miles Madsen, was keeping a watch in front of the apartments of the three people who confessed to killing Justin. Madsen's employment history leads Beckett and Castle to an organisation called Eternal Horizon Institute (EHI). Beckett and Castle go to meet this organisation's leader, Gustavo Bauer. They are surprised to know that he was expecting them. Bauer, however, is available via video conferencing, as he is in Sweden. He says that he did not know Justin or the three people who confessed to killing him. Bauer, also, tells Beckett and Castle that they won't get a search warrant and that is what happens.
Meanwhile, Beckett meets Alexis to know why she does not want to return home. She feels that she might be one of the reasons. Alexis assures Beckett that she is not the reason. She wants to correct her mistake and work hard and pay-off the rent lease, without taking help from Castle.
Miller, Carson and Carruthers are interrogated, together. Certain minute differences in their statements make Castle and Beckett conclude that the murder was not committed in Room 147. Beckett and Castle discover that EHI had organised an event at another Best Traveller hotel. A photo of the event reveals that Bauer knew Justin. Also, the three confessors were part of EHI and had taken part in the event. Also, a doctor informs Castle and Beckett that because of a drug some memories of the confessors have been erased.
Esposito discovers that Bauer made the video call from within his organisation, and not from Sweden. Bauer is found and he confesses to hiring Justin for a program. It was a mock killing and a video was made, as well. Bauer, however, denies that he killed Justin.
The killer turns out to be one of Justin's colleagues at the theatre company. She had killed Justin to see the downfall of EHI, as they were responsible for her brother's death. She did not see Justin as an innocent person because he was involved with EHI.
Case solved and Castle and Beckett are enjoying a sweet moment at home. The doorbell rings and Castle opens the door to find Alexis. She asks her father, "Can I come home?" Castle hugs Alexis and wears a happy father look. Alexis and Beckett look at each other and smile.