Mark Chapman is the snivelling fantasist who murdered John Lennon. By rights he should be no more than a fine-print footnote in pop history, so it's hard to see why he merits a two-hour biopic concentrating on the months before the assassination, especially as the film does nothing but confirm that he was a fame-hungry ego-maniac. "There has never been any choice for me," he mewls in a voiceover that quotes directly from Chapman's journals. "I don't think I ever hugged my father." Your heart bleeds, doesn't it? Contemptible as Chapman is, the film idolises him by paying such reverent attention to his life and thoughts. It's worthless, sordid, tedious stuff.