Infiltration and Suspicion
Driving the plot with a hidden infiltrator or a suspected partner, so characters must test loyalty while trust and identity are constantly in doubt.
How this film uses it
Costigan is a cop pretending to be a criminal. Sullivan is a criminal pretending to be a cop. Anything in the plot that threatens one of them threatens the other. Scorsese cuts back and forth between them, so you end up watching 2 versions of the same trap closing.
Where to see it
The phone call after Queenan's death. Sullivan calls Costigan from a dead man's phone, and each is trying to work out who the other is.


















