"Last Call," 5 p.m., Showtime. Two extraordinary performances, subtle and well tuned, mark this new movie taken from real life. Jeremy Irons plays author F. Scott Fitzgerald in his early 40s. Once the vibrant symbol of the Jazz Age — a phrase he coined — he's been battered by his alcoholism and by his wife's insanity. Feeling like an old man, he hopes to create one more novel. Neve Campbell plays the young woman, a would-be writer, whom he hired to take dictation and type the novel. These are deeply layered people. Campbell is excellent in her quiet role; Irons is extraordinary in capturing Fitzgerald's extremes.