Castle, Season 4

Kevin Ryan:
When I started in Narcotics, I was so green. I-I didn't know how things worked. One day, there's this major bust - street gang cooking meth. They're stacking up guys in the bullpen, taking their statements one by one. Place is a zoo. I'm answering phones in the squad. Girl on the line, name of Alisha, asking for my lieutenant. So I call out across the bullpen "Hey Lou, Alisha's on the phone for you."

[Beckett snorts with laughter]

Kevin Ryan:
It was her tip that got these guys nailed, and all of them just heard me call out her name. Searched all day and all night, looking for her before the gang could get word back to the street that she was a narc.

Beckett:
Well, did you find her?

Kevin Ryan:
I did. Got her into witness protection, but... that was the stupidest thing I'd ever done as a cop. Until the day Jerry Tyson got the drop on me and stole my weapon.