Lisa Edelstein, Stana Katic Lisa Edelstein, Stana Katic

Is this the woman who will come between Rick Castle (Nathan Fillion) and Kate Beckett (Stana Katic)? Former House star Lisa Edelstein begins a three-episode Castle arc as investigator Rachel McCord, who is connected to Beckett's job offer in Washington, D.C., in the ABC drama's Sept. 23 premiere. "McCord becomes a mentor to Beckett and doesn't quite understand why Castle is hanging around," Edelstein says. "What McCord's done with her life is really inspiring and tempting to Beckett, but it is also threatening to the way of life Beckett's chosen so far." 

Edelstein admits she still hasn't watched the 2012 series finale of House, which aired one year after her character, Dr. Cuddy, was written off the show under ugly circumstances when contract negotiations did not work out. "I wasn't happy with how my character ended at all," she says. "It was a really complicated and upsetting situation, which is why I decided not to do the finale. It was horrible and there was no amount of money that would have made it OK."

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