Heat.
Wild that this is already 22 years old. What a great cast and everyone puts in solid performances - especially the two leads, acting together for the first time.
Still holds up and has some of the best action sequences ever filmed sans CGI. Cool that Michael Mann gave Tom Noonan a cameo. Noonan was the original Red Dragon in Mann's 1986 movie Manhunter. (check it out if you've never seen it - solid and maybe better than the remake)
The diner scene with Pacino and DeNiro is so classic. Love that Mann filmed it live using multiple cameras instead of resorting to the old "film all lines by one actor, and then all lines from the other, and then cut and paste them together to simulate a conversation". DeNiro has said that they did 5 or 6 takes and then mutually chose the best one.
The majority of the scene is dead serious, but towards the end both guys give each other a tiny smile, acknowledging the mutual respect between them.