“Joker” is an origin story with a twist – a deeply disturbing descent into madness driven by a tour de force performance from Joaquin Phoenix.

As the title character, Phoenix is an unnerving ticking time bomb that slowly erupts on screen – building to a explosive crescendo in the excellent final act.

“Joker” tells the story of Arthur Fleck (Phoenix), a mentally ill young man who is trying to find himself. Fleck has dreams of going into stand-up comedy, specifically appearing on a late-night talk show hosted by Murray Franklin (Robert De Niro), but he is saddled with a dead-end job and the responsibility of caring for his ailing mother (Frances Conroy).

Fleck has been considered an outcast by society throughout his life, constantly ridiculed and picked on by others. One day, Fleck fights back and discovers he has no remorse for his actions.

While Fleck comes to terms with his new feelings, he also starts to uncover secrets from his past – further awakening the demons from within.

Director Todd Phillips, who co-wrote the screenplay with Scott Silver, might not seem to be the right fit for this material considering his previous work (“The Hangover” films and “Old School,” to name a few), but he brings an intimate, cynical view that works quite well in “Joker.” This is a script that has drawn comparisons to a couple of Martin Scorsese films – “The King of Comedy” and “Taxi Driver” – but I feel is more in line with the recent Dan Gilroy film “Nightcrawler” in its portrait of a disturbed individual.

It helps that Phillips has an actor like Phoenix willing to do whatever is necessary to make the material work. Phoenix completely morphs into this role, with a startling physical transformation, but also makes Fleck so guarded that it’s easy to at least understand why he morphs into the madman that he eventually becomes.

Phillips and Silver try to fill out the screenplay around the performance with spotty success. There are some interesting nods to Batman that bring the two stories together in an intriguing manner, but the attempts to add social commentary about class structure and mental illness don’t always hit the intended mark.

It all comes back to Phoenix, who is a one-man show. Whether he’s talking to a social worker, a sympathetic neighbor (Zazie Beetz) or going toe-to-toe with De Niro in the film’s magnificent final act (if the first two acts were as good as the last we would be talking about an instant classic), Phoenix commands your attention like no other performance from 2019.

An Oscar nomination seems almost a given for Phoenix’s work here, with a best actor win not out of the question.

– To get Micheal Compton’s reviews of “Aquerela” visit his blog at bgdailynews.com/blogs/reel_to_reel or follow him on Twitter @mcompton428. Email him at mcompton@bgdailynews.com

Starring: Joaquin Phoenix, Robert DeNiro

Directed by: Todd Phillips

Rating: R for strong bloody violence, disturbing behavior, language and brief sexual images

Playing at: Regal Bowling Green Stadium 12, Regal Greenwood Mall Stadium 10, Highland Cinemas (Glasgow)

Grade: B