Plot summary
Finch receives 38 numbers, all members of HR. Carter intercepts a drug delivery of the Russian mob, causing leader Peter Yogorov to suspect HR. Carter starts a war between HR and the Russians by firing sniper shots at HR leader Alonzo Quinn, who blames the Russians. Quinn orders his right-hand man, Simmons, to have his men round up the Russians. Reese learns about Carter's plan, and Finch deduces Quinn's identity as the head of HR. The Russians' numbers come up as they are now threatened by HR, but both groups are arrested by the FBI when Carter tips them off.
Carter takes Yogorov into protective custody and has him sign a statement that can earn an arrest warrant for Quinn, but the judge she approaches is member of HR. Quinn, Simmons, and two other HR cops wait for Carter at the judge's house, where Carter reveals that she called Reese and Finch, recording HR's incriminating conversation. Reese breaks in, a shootout ensues, and Carter apprehends Quinn. Simmons later accesses a dashcam that has a picture of Reese.
Credits
Adapted from Wikipedia contributors, Person of Interest season 3. HTML formatting and reference markers removed.