The Third Man (1949)
Directed in fact by Carol Reed, this features a pulp-fiction writer, Holly Martins, visiting post-war Vienna following an invitation from friend Harry Lime. However, on arrival there he finds that Lime has been killed in a traffic accident. What has happened? A compelling story (that only marginally weakens its hold once you’ve already seen it and know the twist), a wonderful music score, fantastic writers (Graham Greene, Alexander Konda, Carol Reed, and Orson Welles), with Welles in the cast along with some fine actors including the excellent Trevor Howard and Bernard Lee.