Wow!... Just wow!... I wasn't expecting to be so thrown with the final scene because despite all my insight on the possible outcome I never even imagined they'd go to such intriguing lengths!
For the sake of not giving any spoilers, I will not say anything more regarding the story structure here. But I can assure you that it really is rare to find, especially on TV. The pathways, clues and emotional investments have been used so originally in this one that, I can even say the delicacy of writing elevates to that of some unforgettable Columbo episodes.
Then why give it a 9 and not a 10?
Just one thing: The direction of the episode and the initial presentation of the case fails to make us ready for such an outstanding detective story with unforesseable twists and turns. More importantly, Castle's personal involvement in the case had to be better underlined somehow. The way they framed such a high caliber story was lame. Stronger drama with more in-depth observation of Castle's bias would not hurt, nor would it steal away from the totally unpredictable surprise ahead.
Yes, they had a gem alright, but they didn't shine it as best they could. And that's the only reason I subtract that single point for my score.
