Unleashed (2005)

On and beneath the meanest streets of Glasgow, fiery gangster Bart is merciless with debtors, would-be rivals, and anyone else to whom he even takes a passing dislike. He maintains his chokehold through his unwilling enforcer Danny, who he has raised since boyhood. Danny has been kept as a near-prisoner, trained to attack and, if necessary, kill. Danny knows little of life except the brutal existence that Bart has so crudely and cruelly fashioned for him. But when Danny has a chance encounter with soft-spoken blind piano tuner Sam, he senses true kindness and compassion for the first time.

Official website: http://unleashedmovie.com/