Movies are often criticised for their lack of fidelity, for not keeping faith with their sources, especially novels, their audience, or their glorious antecedents. Infidelity is also a key plot device, especially of genre films: melodrama, comedy, crime, even the western. We keep going back to the movies partly because they don’t give us what we want. The New York poet Frank O’Hara suggests this in ‘An Image of Leda’, his breathless adaptation of the myth of Leda and the Swan as an allegory for watching films: