"Nikki Heat" has a gimmick in the form of an actress who tries a little too hard to be Beckett, but it's a good gimmick. The episode benefits greatly without a Alexis subplot, allowing for Laura Prepon to be on screen for a majority of the episode, as we see her character, the actress playing Nikki Heat, evolve from the actress disliked by Castle but loved by Beckett, to the complete opposite.
Castle appreciates her dedication to the role and sees that she's smarter than she seems while Beckett, understandably, gets irritated when she nearly takes over for Beckett. The added dynamic of a third-party was very funny, and I would love to see Laura Prepon return. Maybe for the inevitable Nikki Heat sequel?
Score 9.1/10
