Blue Bloods Season 13 Episode 4 revolves around people having to stand up to political pressure to do what's right.

When the Mayor's office demands that Frank reopen an investigation into a police shooting months after the cop was acquitted, no one on the Dream Team is happy; however, Garrett doesn't think defying the mayor is a good idea. Frank wants to deal in facts, not appease people who hate the police, but isn't sure he has a choice. But when Lester offers to resign, Frank refuses to accept it because he needs him in the fight to have police officers treated fairly.

Meanwhile, Crawford makes Erin try to get a confession out of the accomplice of a man she just convicted for robbery. The only evidence of guilt is that the convicted man claims this guy stood lookout; Erin soon begins to believe he is innocent, but the mayor's office wants him locked up ASAP.

Elsewhere, Danny and Baez investigate a string of armed robberies in which the perps steal expensive watches, while Jamie is assigned the task of finding a new hire for FIO.

To find out what happens, watch Blue Bloods Season 13 Episode 4 online.