Interesting episode. Its opening seemed more like a typical House
opening, with the patient showing symptoms during a normal event, than a typical Castle
opening, with the victim found already dead. But I guess it had to be so under the circumstances.
I'm glad they acknowledged that the incident would cause a mistrial, and had the investigation take place between trials of the defendant. That way, they avoided a lot of the usual legal malarkey about investigations continuing during a trial and other sorts of courtroom melodrama.
It's also a relief to finally get an Alexis-heavy episode again. She's been largely absent for most of the season, I'd guess because of Molly C. Quinn's academic commitments. It's good to see her featured more again, though I am getting a little tired both of Castle being unjustifiably suspicious/protective of his daughter and of Alexis being so idealized. I mean, I love it that she's such a great person, but sometimes it's a little hagiographic.