Awesome episode. Great to get back into the mom-murder arc (though it's refreshing to have a modern show that understands it's okay for an arc to just be revisited once in a while rather than be constantly serialized). There were some really good character moments -- with Beckett and Castle (and was this the first time they both called each other by their first names in the same episode?) and with Castle and Martha (a shame there was no Alexis, though). I loved the reveal of Beckett's secret homemade case board. It's like she showed Castle her Batcave (and yeah, that came out sounding naughtier than I intended).
Still, I'm a little disappointed that so little real progress was made. Well, I guess there was some progress. Last time, we found out who shot Beckett's mom. This time, we found out why. What's left is finding out who the ultimate mastermind is and what this bigger conspiracy is.
(You know, there was a moment, when Captain Montgomery refused to let Beckett come into the 12th even though she said she'd be safest there, that I wondered if he might turn out to be the Big Bad. That'd be a daring twist.)
But I'm annoyed at Castle's failure of basic genre-savviness in the teaser. I mean, come on, a guy wants to reveal a killer's name, but instead of just saying it, he gives a long, rambling preliminary speech? Come on, that pretty much guarantees he'll be shot before he finishes! I kept waiting for Castle to point that out and urge the guy to stop burying the lead. (I remember a Get Smart
episode where a character was sufficiently genre-savvy that the very first thing he said was the killer's name, but Max forgot it and the guy was shot before he could repeat it. Or something like that.)