There was no time-traveling killer this week on Castle, much to the chagrin of the show's title character.

But he might need to prepare himself for an even more frightening scenario on the October 18 episode of this ABC hit: Gina getting close to Alexis.

As for the featured investigation on "Anatomy of a Murder," it will center around a dead doctor and Beckett and Castle's venturing into the world of bed-hopping physicians in order to determine the killer. Get an early look at this installment now:

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