In the Season 3 finale of Castle, Beckett, Castle, Ryan, and Esposito all agreed to bury Captain Montgomery's secrets and let him die a hero. After all, he did sacrifice his life to save the beloved homicide detective.
But as we all know, Montgomery had a deep, dark secret — his involvement in the shooting of undercover FBI agent Bob Armen, which sparked the events that led to Johanna Beckett's murder in 1999.
Kate never got over her mother's death and made it her life's mission to find closure. Instead of telling the new captain the truth about Monty's involvement, knowing she'd likely be pulled off the case, Beckett continued pursuing leads on her own, knowing full well that the people involved still wanted her dead.
But all that stopped when Castle worked a deal with Monty's friend Mr. Smith — as long as Beckett stayed away from the evidence, her life would be spared. Castle kept the detective distracted, and continued working the case on his own.
For about a year, all was quiet on the Johanna Beckett front — until a thief on a "clean-up" job broke into Montgomery's widow's house and wound up dead in the Season 4 finale. Castle begged Beckett to step away from the case, exposing his secret deal with Mr. Smith, but the headstrong detective refused.
When Beckett and Esposito found a lead on the killer's whereabouts, they went on a rogue mission to track him down — without backup. Detective Ryan did his best to talk the pair out of it, to no avail. Still worried, he called Rick Castle's cell, but got no response. His last resort was to tell Captain Gates the truth — which he did, thankfully — saving Beckett from plummeting to her death.
But Ryan's confession was a double-edged sword — coming clean also meant risking his relationship with Esposito, who was forced to turn in his badge as a result. Not only did Ryan lose a friend, but he also lost a partner.
At the end of the episode, Ryan's clearly struggling with the consequences of his decision. But should he feel guilty? Or can he rest assured, knowing he did the right thing?
Lindsay Dreyer is an editor at Wetpaint Entertainment. Follow her on Twitter @LindsayNYC.