Season synopsis
Contains spoilers for this season and earlier seasons.
Beckett accepts Castle’s proposal and takes the Washington job, beginning a long-distance engagement. Castle’s surprise visit draws him into a classified case and exposes him to a deadly toxin, leaving Beckett and her new partner Rachel McCord searching for an antidote. He survives, but Beckett’s federal career ends when an ethical disagreement costs her the job. Back in New York, a hostage investigation helps secure her return to the precinct, where the couple can work together again.
Wedding plans run alongside cases that bring old threats back into focus. Murder victims made to resemble Lanie and Esposito lead Castle toward plastic surgeon Kelly Nieman and his suspicion that Jerry Tyson is still alive. Beckett’s undercover work also exposes connections between drug money and Bracken’s presidential ambitions. When she is framed for murder, a recording left by Montgomery supplies the evidence she needs: Bracken’s own words connect him to Johanna Beckett’s killing. Beckett arrests him publicly and finally closes her mother’s case.
Their wedding meets another obstacle when Beckett discovers that an impulsive Las Vegas ceremony years earlier made her legally married to Rogan O’Leary. Finding him turns into a kidnapping investigation involving blackmail and a fugitive hitman. Castle and Beckett get the divorce papers signed and prepare for a ceremony at the Hamptons house after their venue burns down. Then Castle fails to arrive. Beckett reaches the roadside to find his car engulfed in flames, with his fate unknown.