Most everybody loves a good con movie. While the thrill of the illegality of it all – the curiosities, the impossibilities, the big reveal – is ostensibly what makes heist flicks appealing, the fact that everything about the crime subgenre seems so damn stylish is probably more of a reason to keep making films about con artists (and more of a reason to keep watching them). The Sting remains the ultimate con movie, super stylish from start to finish, and everything that followed owes a great deal to that film. But even recent takes like Inception and American Hustle breathe new life into the idea by inhabiting a distinct aesthetic niche.

This is taking the long way around the barn to say that David Mamet’s The Spanish Prisoner, through it is very much a part of the aforementioned genre, is a surprisingly and suspiciously unstylish little film. It’s extremely well-written, as is almost everything Mamet touches, but it’s noticeably devoid of any of the visual trickery or larger-than-life characters that we might expect. This isn’t necessarily a bad thing, but it does mean that The Spanish Prisoner promises a lot in the first act and doesn’t quite deliver on that promise when all is said and done.

Joe is our main character, very obviously filling the shoes of the “mark” from the first scene of the film. This clarity – that we know Joe is being duped as the film progresses – is another thing that sets The Spanish Prisoner apart from other con movies. We know he’s being had, but we don’t know exactly how. Steve Martin gives a rare straight-man performance as the slippery Jimmy Dell, and if there is any flashiness to be found in the muted straightforwardness of the movie, it’s in Martin’s performance. Jimmy Dell is a jerk in one scene, a generous man in the next, a childish rich boy who suddenly becomes a polished advisor before your eyes. The flashiness isn’t your typical Steve Martin flashiness, nor is Jimmy Dell the kind of straight part you’d expect Martin to take. There’s something creepy about Martin’s Dell, and part of it may come from the way the film is structured. It’s not that Dell is written to be that way – it’s that The Spanish Prisoner assumes you know Jimmy is not to be trusted, but it still holds on to his motives for the majority of the film anyway. This uncertainty is the best part of the movie, and Martin plays to that strength.

There are obvious weak points. Joe doesn’t really behave as if anything could ever possibly be untrustworthy about Jimmy, which at times speaks to his naivety and at times just seems too convenient. Joe goes out of his way to buy a gift for Jimmy’s “sister”, which provides the catalyst for his discovery that Jimmy, of course, doesn’t even have a sister – but why would he buy the gift in the first place? He’s an extremely busy guy with a lot of work problems to contend with, and buying a gift for someone he’s never even met is slightly odd. It might be a small point, but it leads to a massive realization on Joe’s part and ultimately seems a bit contrived.

The ending, too, leaves much to be desired. Jimmy Dell disappears from the movie only to arise again in the final moments, and the dialogue here is strangely unemotional. Dell could have been an iconic, memorable character, and Martin plays him that way for the first two acts of the film. But this climax is weak, on Mamet’s part as both writer and director and on the part of the actors involved, who fail to bring much urgency to the situation. Jimmy resurfaces and is put down a second later, and there’s not even a wrap-it-up scene for our viewing pleasure – The Spanish Prisoner just ends, as if it feels the need to concede that it just has nothing else to say.

Again, the relative unadornedness of the film is actually somewhat refreshing, certainly more true-to-life than most con flicks can manage. And again, Martin is the real star here. Mamet’s set-up is all the more impressive considering the unexciting manner in which the movie ends, but it’s Martin’s Dell who carries us from one point to the other. He’s played plenty of straight-man characters alongside his zany Inspector Clousseau-types, but Jimmy Dell exudes more potential in his first few scenes than most of those others allude to in the entire runtime. He’s the only real surprise to be found in The Spanish Prisoner.