'The Dark Knight' at 15, Christopher Nolan's movie is still a rare treat — even if you take away the superhero costumes

• Christopher Nolan's "The Dark Knight" debuted in theaters on July 18, 2008.
• The film pits Christian Bale's Batman against Heath Ledger's Joker.
• It's seen as one of the best superhero movies ever made, and it would still work without the costumes.

It's not exactly controversial to say that Christopher Nolan's "The Dark Knight" is one of the best superhero movies ever made. It frequently tops "best of" lists, with many critics praising the battle between Christian Bale's bat-brained vigilante and Heath Ledger's chaotic Joker.

But at its heart, "The Dark Knight" isn't a superhero movie, not really. It's a crime thriller with a few outlandish outfits. After all, the story hinges on political corruption in the mayor's office and in the Gotham City Police Department, which allows the mob to move its dirty money around the city and into off-shore accounts. 

It's a far cry from a typical superhero "magic orb" plot, where a costumed crusader has to stop a bad guy from getting a specific object in order to save the universe — sorry Marvel, but it's been done to death. 

If you took Bruce Wayne's military-grade weapons and body armor bat suit away from him, the story would pretty much work the same. It would still be about a man determined to root out injustice and corruption from his city, while also grappling with a domestic terrorist who revels in chaos.

Heath Ledger's Joker is one of the purest and most blood-chilling villains because he isn't weighed down by a tragic, complicated origin story. He simply wages a psychological war of terror on Gotham in an attempt to make the city destroy itself. His methods and motivations are chaos. 

That lack of justification makes the Joker all the more terrifying — no colorful costume and decrepit face paint needed.

Nolan's grounded approach makes things far more fascinating than the typical CGI battles audiences are used to. One of the most powerful (and intimidating) scenes of the film is Batman trying to interrogate the Joker at the GCPD.

Ledger and Bale give truly dedicated performances that pull the audience to the edge of their seats. It's a masterclass in tension.

Batman will stop at nothing to save people, dishing out brutality as an interrogation technique, whereas the Joker simply can't be bargained with — and he enjoys the power that gives him over people. It's the type of script we don't see as often in the superhero genre anymore.

Unfortunately, in the 15 years since its release, studios seem to have taken the wrong cues from Nolan's Batman trilogy — not everything needs to be injected with gritty realism. Instead, filmmakers should ask themselves if their films, like Nolan's, can stand on their own without the high-octane stunts, overcomplicated multiverses, and silly capes.