Time to Apply to Law School
Beckett is pretty shaken up by this murder. She had deduced that Marks was the conduit between Vulcan Simmons' drug money and Senator Bracken's presidential campaign, but now that he's dead she has one less chance of taking down her mother's killer. A traffic camera reveals that Simmons was driving the car Beckett saw Marks get into, but Simmons' lawyers get him off just by saying that it was someone else in the pictures. Being a lawyer doesn't seem all that hard. Even though he's already got this ironclad defense, Simmons can use Beckett's documented hatred of him to prove police bias and Gates has to take her off the case.
Because Beckett has not had a complete personality transplant, she doesn't follow orders. She uses her stalker pictures to figure out where Simmons is storing the car, and when she gets there she finds Marks' blood on the seats. But Simmons is waiting for her and points out that her breaking into his garage without a warrant makes the car evidence inadmissible. She keeps holding him at gunpoint, and the next day Simmons is found shot to death.
On the Run
Except for all of Beckett's actions in the past six seasons of Castle, all of the evidence points to her as the killer. Simmons was apparently tortured for information before being fatally shot, and the murderer removed all the evidence the police normally look for. But things really start to look bad when a bullet is found in Simmons' body that's traced back to Beckett's gun. Someone broke into her apartment and stole one of the several guns she owns in order to frame her for the crime. Internal Affairs arrives, and even though no one at the precinct believes Beckett would kill Simmons, IA does. She gets out just before they put the building on lockdown.
Castle and Beckett meet up at their proposal swing. Beckett realizes that Bracken is trying to eliminate her entirely; he must have found out that she doesn't have the destroyed file she'd been blackmailing him with, and now he wants to get rid of her for good. Castle has learned that Montgomery's friend Smith, who died a while ago protecting said file, actually faked his death. They go to the hospital where he died to try and get information from his doctor, but the fact that Beckett's a fugitive makes interrogation difficult.
Word does reach Smith that they're looking for him, and he's conveniently close enough for a shadowy meeting. Smith explains that he had been working with Marks to try and take down Bracken so that he could resume his old life. The only other hope, he says, is a possibly non-existent tape recording on which Bracken allegedly admits to murder. It had been recorded by a former associate of Bracken's, but no one knows what happened to it or if it's even real. When Castle and Beckett ask where they should look for it, Smith tells them that they're screwed and that they should leave the country. Thanks for the optimism!
Murder Builds Character
Castle seems pretty okay with the idea of leaving everything behind and living on the run. You know you have a kid, right? And that if you leave without her she'll be targeted? And you have a co-dependent mother? And you're pretty famous? Clearly, this is not an idea he's thought through. Beckett wants to stay and keep fighting, but Castle goes ahead and starts making poorly-conceived plans.
While Beckett waits for him and prepares to go blonde, Bracken and his hired guns break into her motel room. Which sucks, but she did dodge a bullet with the almost-going-blonde thing. He then proceeds to take credit for all of Beckett's accomplishments in life because murdering her mother really toughened her up. Beckett responds by challenging Bracken to have the guts to kill her himself instead of having one of his goons do it. Bracken declines, because he's too smart to leave physical evidence, and then risks leaving physical evidence by stroking Beckett's cheek. Gross.
Once he's gone, Bracken's lackeys force drugs and alcohol on Beckett in order to stage a suicide. When they go to help her inebriated self pull the trigger, she spits the unswallowed drugs back in their faces and kicks some ass. It's very nearly a flawless victory, but she gets a pretty nasty head wound in the process and passes out in the hall.
Truth Conquers All
When Beckett comes to, she and Castle are on the way to Canada. Again, no mention of Castle's beloved child is made. Beckett tells him to turn around, because while unconscious she'd had a revelation. She remembered her first meeting with Montgomery, when she was just a lowly patrol officer sneaking around the archives looking for info on her mother.
Montgomery had suggested that she look through her mother's things instead, and Beckett realizes that Montgomery must have made the tape and given it to her mom. It's a pretty big leap, considering she figured this out in a concussion dream, but she and Castle go with it and turn back towards New York.
By this point, Ryan and Esposito have filled Gates in on all the details of Johanna Beckett's murder and Bracken's corruption. She believes them completely, but doesn't know what they can do about the situation. The only help Ryan and Esposito can give is by distracting the police officers stationed at Beckett's apartment so that she can get in and look through her mother's things. They find her mother's datebook, which is written in an insane code, and from this gather that she must have had the tapes on her when she died. It's yet another leap, but they don't get a chance to investigate further because IA bursts in and arrests everyone.
Things are looking pretty grim. Castle and Beckett lament the fact that they won't be able to get married now, and that they still have nothing on Bracken. But then Beckett looks over at her desk and sees her ever-present elephant family. It belonged to her mother before her, and she breaks it apart to reveal a cassette tape from approximately the same year as I was born. It's such a wonderful inclusion to have something so crucial to the show's main mystery hidden in something we see in almost every episode. The handling of this arc has been really choppy this season, so it needed a redeeming detail like this.
Luckily, the tape still works, and it is delightfully incriminating. Finally having what she's been searching for most of her life, Beckett interrupts Bracken's press conference and arrests him in front of the media. It's a moving scene, and I'm glad she got to hand out such public and humiliating justice. I don't really believe this saga is over, but for now, it's hard not to be satisfied.