Batman returned to the cave after shaking down some mobsters. Dick said he was ready for the final exam. Batman set it up for the July 4 weekend.
Alfred dropped him off in the city - Robin had a six hour head start on Batman and had to remain hidden from him until sunrise. Within a couple of hours, Robin happened upon a mob hit. He stopped it and grabbed a piece of evidence the victim wanted to get to Gordon.
Batman met with Gordon - the victim was an undercover. He had an APB out on the costumed kid who interfered and snatched the evidence. Batman began following clues Robin had left him to his location. He dropped in on Joe Minette and told him to stay away from the boy. Minette doubled his efforts; Robin ran into trouble and ended up jumping from a bridge. He was captured at gunpoint in the sewers.
Batman got a lead after roughing up some of Minette's men. He found Robin just in time to see him escape and take down Minette's men. Minette himself chased the boy onto the barge carrying the fireworks for the Independence Day celebration. Shots were fired, and the fireworks lit up. Minette found Robin about to bail from the boat and grabbed him. He saw a silhouette of Batman and lost his cool. Robin grabbed his gun and tossed him into the river.
Batman congratulated Robin, though he made mistakes, and introduced him to Gordon.