About Robert De Niro and Sylvester Stallone star as old boxing rivals who come out of retirement for one final match. On their first encounter in decades, their long-festering feud erupts into an unintentionally hilarious melee that instantly goes viral. The sudden social media frenzy transforms their local grudge match into a must-see HBO event. Now, if they can just survive the training, they may actually live to fight again. -- (C) Warner Bros.