Today's scene comes from the most tense scene of all of them.
On an unrelated note, I haven't seen Infernal Affairs, which The Departed is based off of. If anyone's seen it and has an opinion about it, I'm all ears.
Sullivan Calls Costigan
Costigan's two closest allies - the ones who know who he really is - are dead and disappeared. Clearly, he's seen better days. On the other side, Sullivan is within spitting distance of determining the identity of the law's mole within Costello's mob, but is denied access.
Bad for the two leads, but since Sullivan has Queenan's phone, it's good for us. The phone is the one Queenan used to contact his inside man, so all that remains is to see who picks up.
When the phone goes off, the look on Costigan's face is priceless. The nearly dialog-free moments that follow are even better.