Destroyer (2018) on Netflix

Plot summary

LAPD detective Erin Bell arrives at the scene of an unidentified man's murder and tells the responding officers she knows who killed him. At the station she is handed an envelope containing a hundred-dollar bill stained by a dye pack; an FBI contact traces it to a California gang's bank robbery sixteen years earlier, when Erin and FBI agent Chris were embedded in the gang as undercover officers. Erin takes the bill as a sign that Silas, who led the gang, is active again, and she begins working through the members she can still find, among them Toby, dying on compassionate release, Arturo, and the lawyer DiFranco. Flashbacks show a younger Erin and Chris going over their covers as a couple. In the present, Erin's daughter Shelby lives with Ethan.