For some it's a violation of instructions, but for Detective James Knight it's a regular day at work. While hunting for robbers, the elderly cop broke the law and ended up in jail. While his friend and partner Fitzgerald is re-learning to walk after being wounded, Knight plays cards with other prisoners and attends Christian meetings of the preacher Father Conlan. On Christmas Eve, Knight is released, at which point New York City is attacked by a squad of terrorists dressed as Santa Clauses. The policeman begins to search for the gang, not suspecting that the ringleader of the holiday grandfathers he knows well.