Fifteen years ago, former Palais Elite Agent Lisa Miller abandoned her violent career to live anonymously in Riverford, raising her daughter Harley while running a barbecue stall. When Harley is bullied by Finn Lopez, son of a powerful family, Lisa confronts him, inadvertently triggering a chain of revenge. Finn kidnaps Harley and attempts assault, but during her escape, Harley accidentally kills Finn’s father Richard during a confrontation. Richard’s mafia-linked family retaliates by targeting Harley again.
With help from Riverford Governor Haider Fain, Lisa temporarily imprisons Richard, only to discover his ties to a shadowy mafia group connected to her former organization, the Palais Team. Using her dormant agent skills and Haider’s resources, Lisa rescues Harley and dismantles the syndicate.
Uncovering the Palais Team’s corruption, Lisa reclaims her codename "Lady Nightingale," infiltrates their leadership conference, and reforms the organization to its original purpose. After restoring its integrity, she shocks allies by retiring again, choosing a quiet life with Harley over power.