The team doubts whether Broyles can be trusted on Fringe. "The Bullet that Saved the World" is the fourth episode of the show's fifth and final season.
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Fringe Season 5 Episode 4 Quotes

Peter: You had to give up your necklace so we could work on the laser. I wanted to make sure you got a new one.
Etta: Thank you.
Peter: Worth every bump and bruise kiddo.
Etta: Well, you know the expression. No good deed goes unpunished.

Olivia: How is it coming?
Walter: Fast as a snail! At this rate, we'll save the world in another 21 years!