Kate Beckett's investigation into her mother's death is reactivated when Hal Lockwood - a professional hitman with knowledge of Beckett's mother's murder - stages a spectacular escape during a court hearing. As police launch a manhunt for Lockwood, Castle and the team uncover evidence of a deeper conspiracy involving a mysterious figure with law enforcement connections who is linked to both Lockwood's escape and the killing of Johanna Beckett. The search for Lockwood and the quest to identify his co-conspirator leads to a shocking and deadly conclusion.
Spoilers ahead. Coverage follows the scope labeled below.
Complete story — includes the ending
An assassin with knowledge of the details behind Beckett's mother's murder escapes from custody during his arraignment, leaving Castle and Beckett to track him down. Secrets are revealed about Captain Montgomery's past as the third cop. Montgomery leaves evidence of his involvement with a powerful outside party in the case for Beckett, before confronting the assassins. He is shot and killed in the process. At Montgomery's funeral, Beckett is shot in the chest by a sniper. Castle tells her that he loves her as he holds her in his arms just before her eyes close.