Rick looks oblivious to the professional killer he's about to face. Maybe he can use it in the next book, if he survives.

What is Rick holding and is there any chance it will help him fight off a ninja? "The Way of the Ninja" is the 18th episode of the show's sixth season.

Castle can't believe his eyes. Who actually expects to face off with a ninja? Well, maybe Castle.

Beckett and Castle are in a big empty space. Little do they realize what type of visitors may be lurking in wait.

Do Kate and Rick have any idea they are about to face off with a ninja. "The Way of the Ninja" is scheduled to air Monday, March 17th on ABC.

Does Rick have something better to do? Beckett looks annoyed on Castle Season 6 Episode 18.

It's as though it's come straight of of Rick's imagination. Castle actually faces a ninja.

Will Capt. Gates and the team at the 12th precinct be able to help Kate when she meets a dangerous man from her past while undercover? And why isn't Rick in any of these photos from "In the Belly of the Beast" set to air Monday, March 3rd on ABC?

Esposito always has Beckett's back. How will he feel about her going undercover without her team?

Esposito and Ryan don't look happy when they find out Beckett's going undercover. Will they be able to help when the operation goes horribly wrong?

Is this the man who pulls Beckett in to a deadly undercover Narcotics operation? "In the Belly of the Beast" is the 17th episode of the show's sixth season.

Beckett comes face to face with a dangerous person from her past. Will she get out of her undercover operation alive?