The former doctor is in.

TV Line confirms that Lisa Edelstein - best known for her long-time role on House before stopping by The Good Wife and Scandal last year - will appear on multiple upcoming episodes of Castle.

Look for the popular actress to star as Rachel McCord, a federal investigator who plays a key role in Kate Beckett's pending decision: Will she take a new in D.C. or stay with her wanna be fiance in New York?

Considering Edelstein is booked for more than one appearance, and assuming she is based out of Washington, does this move signal where Beckett will end up on Castle season 6? Stay tuned.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.