Caskett shippers, you will get some closure during the "Castle" Season 4 finale. One way or another, Castle (Nathan Fillion) and Beckett (Stana Katic) will confront their feelings about each other.
"We advertised this season as a season of secrets," explains "Castle" creator Andrew Marlowe. "Beckett was withholding from Castle that she heard him say 'I love you,' and Castle has a secret from Beckett about the mysterious phone call that he received about protecting her and keeping her away from her mother's murder."
Secrets are eventually revealed, though, and this situation is no exception. "We knew when we hit the end of the season that the secrets were going to come out," Marlowe tells Zap2it. "Before we get to the finale all of the secrets are out and the characters have to deal with the emotional consequences of that, both how they feel about each other and how they feel about being betrayed by the other one."
Although the characters got back to their usual Castle-Beckett fun (witty banter, playful bickering, etc.) in "Undead Again," the underlying tension means it won't last. "All of where we are arrived at in 'Undead Again' gets knocked on its ass in the finale. We have to confront some of the more difficult aspects of their relationship. We go to the core of what they've been dealing with for the last year, and we also put our cards on the table of how they feel about each other and how they felt about each other for the past four years. So it ends up being a really explosive episode, the finale."
As for the other ongoing storyline -- the mystery surrounding Beckett's mom's murder -- "we start to get answers," Marlowe promises. "We are on the downhill slope. We don't complicate it any further, and we start edging towards answers. We make the audience a pretty significant promise that that mythology is not going to go on forever."
um i just got done watching it and without giving it away, this is my succint emotion on that ending: