Dexter and Rita take Harrison to the doctor in this clip from Dexter. It's courtesy of the episode "Lost Boys."
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This is a clip from the Dexter episode "Lost Boys." In it, Trinity is tracking a new victim... while Dexter is tracking Trinity.
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Check out the official Showtime preview for "Lost Boys." In it, Dexter discovers something new about Trinity.
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Dexter Season 4 Episode 10 Quotes

I know that look. I'm not the only one on a stalk.

Dexter

Dexter: He's never taken a child before.
Harry: That you know of. If this is new, it's on you.