LAPD detective Erin Bell arrives at the scene of a John Doe murder, promptly asserting to the responding officers that she knows the identity of the murderer. Shortly after, she receives a $100 bill, marked by a dye pack, in an unmarked envelope. With the help of a contact at the FBI, she learns that this bill is tied to a bank heist committed years ago by a notorious California gang, the very gang she and her former partner Chris infiltrated as undercover operatives.
Determined to uncover the truth, Erin informs her superiors that the John Doe murder and the bill are signs that the gang’s leader, Silas, is back in business. To locate Silas, she methodically navigates through the remaining gang members, starting with Toby, who is gravely ill and residing with his mother on compassionate release. Using a bold tactic, she persuades Toby to reveal the whereabouts of Arturo (played by Zach Villa), a former gang member now attempting to make amends by offering legal aid to immigrants. From Arturo, Erin learns about Dennis DiFranco, a lawyer laundering the proceeds of their original crime.
Through a mix of intimidation and sheer force, Erin coerces DiFranco into giving her the location of the next money hand-off, which is orchestrated by Petra, Silas's girlfriend. In a riveting turn of events, Erin tracks Petra down and intervenes in a bank heist perpetrated by Silas’s new crew, ultimately taking Petra hostage for information.
As the narrative unfolds through a series of compelling flashbacks, we learn that Erin and Chris shared a profound romantic connection during their undercover days, culminating in Erin's pregnancy. They had plotted to become legitimate by taking their cuts from the heist and subsequently reporting that they had lost contact with the gang. However, their plan went awry when a dye pack detonated, leading to catastrophe: Silas ruthlessly killed an innocent bank teller, and in the ensuing chaos, Chris was fatally shot while trying to protect others.
In the backdrop lies the troubled relationship between Erin and her daughter Shelby (played by Jade Pettyjohn), who is resentful towards Erin and has spiraled into rebellion, seeking solace in a relationship with a no-name individual called Jay (Beau Knapp). Erin's attempts to steer Shelby away from Jay lead her to desperate measures, even resorting to paying him off.
In the present day, after numerous twists and turns, Erin revisits a self-storage unit to claim her share of the ill-gotten gains, only to discover that most of the money is stained with dye. Just then, she receives a text from Silas instructing her to meet at the Sixth Street Viaduct. There, a tense confrontation ensues, resulting in Erin shooting Silas, finally avenging Chris's death. However, the aftermath is grim. The following morning, as police delve into the John Doe murder, it is revealed that Erin has been suffering from internal bleeding due to her investigation. Eventually, overwhelmed by her injuries, she succumbs while seated in her car, leaving behind a trail of secrets and retribution.
