Arthur Bishop, a seasoned assassin known for his ability to make his kills appear as accidents, sees himself as an artist in his craft. With wealth accumulated from his successful hits, he finds himself grappling with feelings of depression and loneliness as he enters middle age. Seeking companionship and perhaps a sense of purpose, Arthur takes on Steve McKenna, the son of one of his victims, as his protege. Training Steve with precision and caution, Arthur introduces him to the world of contract killing and includes him in their dangerous missions. As Steve grows more skilled, Arthur becomes haunted by the fear that his apprentice will uncover the truth behind his father's death and his own involvement in it. The bond between mentor and student becomes increasingly complex, as secrets and betrayals threaten to unravel their deadly partnership.