Blackmail is an action thriller drama that revolves around an honest police inspector named Abhay Rathod (Suniel Shetty). He is assigned the case of a criminal don, Shekhar Mohan (Ajay Devgn), whom he successfully entraps and gets sentenced to jail. Years later, after completing his jail sentence, Shekhar returns to take revenge on Abhay Rathod. He kidnaps Abhay’s son, Chirag (Parth Dave) and the ransom doesn’t involve money but something much more important than money. Shekhar learns that Chirag is his long-lost son. How this news affects everyone’s life forms the rest of the plot.