Convicted wrongly, Carter Elroy has a chance to get back to his old life thanks to a masked man. That man tells Carter that he has to work for him and unless he follows through, his family will be in danger. 
What does the work imply ? Nothing much, Elroy just has destroy lives for him.  If he refuses his family will die and if he accepts he might go back to jail if he happens to get caught. 

The choice is yours Carter Elroy, either way you'll be singing death's melody.