It’s easy to picture how young Doug McKeon, just fifteen years old, might have reacted when he landed a role alongside someone like Hepburn, plus two Fondas and nearly twenty Oscar wins combined. Despite likely feeling apprehensive, he performs well as "Billy," accompanying his father (Dabney Coleman) and his new girlfriend, "Chelsea" (Jane Fonda). Chelsea is the daughter of the grumpy older "Norman" (Henry Fonda) an…