This 1967 French movie is famous for being perhaps the slowest paced thriller ever made; it takes one hour and forty-five minutes to tell a story that most modern American directors could polish off in a pre-title prologue.
Well, I'm kind of kidding. This movie is an acknowledged classic. (So I suppose I should have liked it more.) Alain Delon plays a hitman whose life begins to unravel when the Paris police manage to pick him up as a suspect (by sheer dumb luck) after one of his murders. He takes this more or less in stride; he seems pretty bored by it, in fact.