Markus, a stern military man, is called back home from his deployment when his wife dies in a train accident. His teenage daughter, Mathilde, is left alone and struggling with the loss. Markus tries to console his daughter but finds it difficult to connect with her due to his military background and stoic demeanor.
Later, Markus is approached by a man named Otto, who tells him that he believes his wife's death was not an accident but a meticulously planned assassination. Otto, a statistician and ex-convict, claims to have evidence to support his theory and convinces Markus to help him seek revenge.
Together with Otto and two other misfit companions, Lennart and Emmenthaler, Markus sets out on a mission to hunt down the perpetrators. However, as they dig deeper into the investigation, they uncover a much bigger conspiracy involving a notorious biker gang, rival criminal organizations, and corrupt government officials.
As Markus and his team pursue justice, they must navigate a dangerous and unpredictable world, also confronting their own personal demons along the way. Riders of Justice is an action-packed, darkly comedic tale of revenge, redemption, and the power of human connection.