Stéphanie (Léa Drucker) is tasked with uncovering the truth, but her inquiry collides with institutional resistance and pressure mounts as the case turns personal, forcing her to confront the fragile lines between truth, loyalty, and justice.

As with Dominik Moll's earlier film The Night of the 12th, Case 137 is based on actual events, namely the many instances of police brutality documented during the gilets-jaunes demonstrations in France in 2018.