I’ve already spoiled several new sneak peeks for this coming Monday’s fan friendly, comic-con inspired episode of Castle, “The Final Frontier”. Star Trek: The Next Generation alum, Jonathon Frakes, is directing and promises fans will thoroughly enjoy this ‘crowd-pleasing’ installment. Plus, Beckett will not only be getting in touch with her fangirl side, but her fangirl side will be getting in touch with Kate’s sexy side 
Frakes promises to deliver Nathan Fillion (as Rick) doing an “incredible” William Shatner impression, “much more comedy” than the Season 2 Castle he helmed and all-in-all a “wonderful forum for Beckett to reveal her fangirl side.” (Said simply: There’s photographic evidence of Kate once getting her geek on as a character from the episode’s Nebula-9 show-within-a-show – and her costume just might resurface in an extremely different context before the hour is over.)
Source: TV Line