"You didn't think I'd risk losing the battle for Gotham's soul in a fistfight with you?" replies The Joker when questioned by Batman over his motives in The Dark Knight (2008).

Though he may repeatedly insist that his actions entail simple, mindless violence, The Joker here reveals that there is indeed method to his madness, and that the chaos he strives for contains some semblance of order and end result. That is to corrupt the entire city. And so by way of what little logic The Joker operates on, destroying the city's soul would eliminate its population, like a virus spreading through a computer network. The soul of the city is, by extension, the soul of its people, and when Nolan here links setting with identity, he continues a trend of thriller genre filmmaking using the metropolis as an ideological vehicle.

Hell's Kitchen and Boston - both predominantly Irish-American sprawls - act as canvases to explore wider themes of religion, family and ethnicity in State of Grace (1990) and The Departed (2006) respectively, while the mean streets of Baltimore provide a bitter contradiction to the pastoral Virginian setting that haunts Clarice Sterling in The Silence of the Lambs (1991). Likewise, the nameless, perpetually rainy city of Se7en (1995) channels ideas of anonymity and alienation in the modern age, just as the ally-occupied Vienna in The Third Man (1949) functions to examine the effects of war and violence on a collective psyche.

Fig i: McCauley and Eady in Heat (1995) visually connected to the cityscape

Particularly in the American thriller, the concept of 'the city' serves as a way for filmmakers to convey wider, more universal themes amongst the shootouts and car chases. When The Joker admits that he wishes to corrupt the city's soul, he reveals that he wishes to corrupt everyone within that city, regardless of their role, inexplicably linking the population together as one united, harmonious entity. In a sense, the city here becomes a character in itself. In Gotham, and in Hell's Kitchen, and in Boston, those of the cast not covered by the main narrative are amalgamated into one, and each of their stories comes together to form this so-called 'soul'.

Perhaps the most effective example of this idea is presented in Michael Mann's Heat (1995) wherein Los Angeles provides a backdrop for explorations of masculinity and femininity, criminal morality and the duality of human nature. Mann's vision embraces the idea that life continues to occur around the central characters, whether filmed or not, and through the employment of the city as a cinematic device, he is able to explore not just the lives of protagonists Neil Macaulay and Vincent Hanna, but those of the entire population through their suggested metropolitan connectivity.

Fig ii: Hanna and McCauley in the diner, with the background characters forming much of the mise en scene

Fig iii: Again in the diner, where Mann is careful to work numerous faces into the frames composition

Consider that, In Heat, the visual role of the crowd is especially important. Macaulay and Hanna only ever appear together in two shots: once in the celebrated diner scene, and once at the end of the film on the runway at LAX. In the former, the two find common ground in their absolute conviction to a certain way of life, and notice here that each background character is given equal focus (fig ii), with very few lost to the anonymity of blur and motion (fig iii). Though we are unable to hear what they are saying to each other, Mann reminds us that, whilst his main characters converse, so too does the city around them. In the latter scene, the pair occupy a space completely devoid of life save for each other. Here McCauley is dying, after fleeing to the one place that could remove him from the city's networked equation - The airport. In perhaps the two most important shots in the film, Mann establishes the importance of Los Angeles in this narrative, and the idea that McCauley and Hanna's story is one occurring simultaneously alongside millions of others.

Furthermore, the architecture of Los Angeles plays an integral role in visually representing key character elements. At one point, Hanna angrily refers to his wife's house as "dead-tech, post-modernistic bullshit," (fig iv) playing into his old-world values and totally dismissing the abstract structure. His wife complains that he never opens up, and that his ultra-macho exterior prevents any real relationship. He retorts that her house is too expressive, and too revealing of personality and perhaps weakness. The house, an angular creation by Thom Mayne's Morphosis Architects, is the complete antithesis of Hanna's character. To him, its structure is repulsive for its ambiguity, something he and McCauley seem to detest with their precise and detailed moral codes and systems of value. (fig v)

Fig iv: The Morphosis house Hanna deems too expressive

Fig v: McCauley's house featuring a simple, linear and minimalist design. Due to their similarities, Hanna would presumably prefer this environment.

The characters are inherently linked with the city around them. Many will be born and die there, as characters tend to do in thrillers, be they innocent bystanders or hideous villains. In Heat, the soul of the city is channelled through the few but represents a wider scope of focus. The soul of Los Angeles here may not face the explicit threat of The Joker towards Gotham, though it works more effectively to depict the delicate balance of life that occurs within its borders. The North American thriller has long taken place inside these cities for precisely this reason, its expressiveness when depicting themes larger than one person or narrative.

A weak thriller will tell you that 'the fate of the city hangs In the balance' but a strong thriller, like Heat or Se7en, or many of the others mentioned here, will never need to, because the imposing skylines, jagged architecture and fearful civilian expressions tell you everything you need to know.

Kristofer Thomas is on Twitter @KRSTHMS