In England, the retired Royal Marine Harry Brown spends his lonely life between the hospital where his beloved wife Kath is terminally ill and the chess game with his only friend Leonard Attwell in the barge pub of Sid Rourke. After Kath's death, Len tells his mourning friend that the local gang is harassing him and he is wearing an old self-defense bayonet. Harry suggests going to the police. When Len is beaten and stabbed to death by detective Alice Frampton and her partner Sergeant Terry Hicock, they are sent to investigate. They visit Harry but have no good news. The police have found no evidence other than the bayonet to arrest the Hoodlums. This means that the gang would claim self-defense in the case of a court case. Harry Brown sees that justice is not granted and decides to take the matter into his own hands.