almost – to make up for the fact that the story itself is something of a letdown.A classic unreliable-narrator doc, the film is always fun to watch. But unlike, say, Ramin Bahrani’s “2nd Chance” — a 2022 Sundance doc that is intricately constructed to take the viewer through the twists and evasions doled out by its own unreliable narrator — “My Old School” works hard to put a stylish spin on a story whose surprises are telegraphed from the beginning.It gets off to a promising start, as we see actor Alan Cumming sitting down at a desk in a Scottish classroom, with titles letting us in on the film’s central conceit: “The man at the heart of this story does not want to show his face, but you will hear his voice.