On the episode "Road Kill," Dexter never got a chance to use this kill room. He actually ended up saving Trinity's life instead.
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What is Trinity up to? He takes Dexter along for a road trip on the episode "Road Kill."
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Dexter Season 1 Quotes

There are no secrets in life, just hidden truths that lie beneath the surface.

Dexter Morgan

Tonight's the night. And it's going to happen again, and again. It has to happen. Nice night.

Dexter Morgan