The Killing Joke, the groundbreaking graphic novel by Alan Moore, poses the theory that a truly bad day can turn any rational person into a crazed lunatic like the Joker. In that Batman tale, Joker's experiment on Commissioner Gordon fails, despite some truly horrific acts by the villain.

During the course of the story, however, readers see flashbacks that show the truly bad day -- or, at least, some version of it -- that turned a fairly average, down-on-his-luck guy into the Joker. It is, to my knowledge, the best exploration of the Joker's murky past and the reason he is who he is.

At least, until today, when I finally saw Joker, a controversial movie depiction starring Joaquin Phoenix in the titular role.

In the film, Phoenix is Arthur Fleck, a wanna-be comedian who struggles to get by with a clown-for-hire day job, an ailing mother and a battery of medications to combat his depression and other undisclosed issues. One condition of note is his reflex to laugh, maniacally and uncontrollably, in times of stress.

As things get worse and worse for Arthur -- a random street assault, funding cutbacks that cost him counseling and access to medications, losing his job, and revelations on top of revelations about his own background -- he begins losing his tenuous grip on stability. And when another random incident pushes him too far, he simply snaps.

And, he quickly discovers, the consequences of his actions don't bother him too much.

On top of that, his own acts of violence have the unintended effect of inspiring a citywide protest -- and eventual riot -- by people who feel put down by the system. And, since Arthur is widely identified to the public simply as a suspect in a clown mask, rioters adopt the motif and rally in similar disguises.

To say the film is dark and disturbing is an understatement. It's hard to watch. I mean, really hard. The anguish Arthur suffers, the mental breakdown we are forced to watch, is horrific. And when he laughs, he's laughing in pain.

There's no hero here. And to call Joker an antihero, I think, is to misuse the term. Don't think for a minute viewers are meant to like Arthur Fleck, or to identify with him at any stage of the film. But it's a very real-feeling descent into madness that evokes sympathy, if not empathy, even as the audience recoils at his distorted view of reality and his increasingly violent responses.

It's hard to imagine what Phoenix -- who also lost a dramatic amount of weight for the role -- went through mentally to produce this performance. As hard as it is to watch, it's also a masterful example of the craft, and I can't help but expect an Oscar nod for his work.

Joker is, without question, Phoenix's film. All other roles are secondary, including phenomenal turns by Robert De Niro as talk-show host Murray Franklin and Frances Conroy as Fleck's mother, Penny.

And, while this most definitely is not a Batman film, there are tangible ties to the Batverse, with appearances by Thomas and Martha Wayne (Brett Cullen and Carrie Louise Putrello), a young Bruce Wayne (Dante Pereira-Olson) and Alfred Pennyworth (Douglas Hodge). But, while rumors of a sequel abound, director Todd Phillips has been fairly clear in saying his Joker will never contend with the Batman.

In any case, I hesitate to recommend Joker because it's not a movie you'll walk away from feeling good about ... well, anything. It's dark, depressing, oppressive and absolutely brilliant.