Eva (Knudsen) works as a guard in a prison. The only woman among men. No one knows her true story. No one suspects that under her uniform and apparent calmness she hides a plan of revenge that she has been quietly cultivating for years. Intricate, cold, precise. A plan that has become her obsession, the meaning of existence, the only light in a place where violence and silence rule. When a young man who murdered a cellmate ends up in the high-security ward, Eva makes a decision that puts her entire life at risk.