Rated R. At the AMC Boston Common, AMC South Bay and suburban theaters.

“Beau Is Afraid,” the latest effort from writer-director Ari Aster, begins as an urban horror film of great power. Beau Wassermann (Joaquin Phoenix) is a troubled single man living in a spider-infested apartment complex perhaps in New York City next door to a peep show. Outside a nearly naked young man is dancing non-stop some sort of rumba on the sidewalk. News report tells of a fully naked man who has stabbed someone to death on the street. He is also on the scene.

Beau, returning from a session with his therapist (Stephen McKinley Henderson), where the talk is about Beau’s mother, must race with a tattooed maniac to get to his building’s front door first. At night, street noises keep Beau awake. Also keeping him awake is a neighbor slipping notes under his door and one who turns up the music. Someone steals Beau’s keys, making it impossible for him to catch a plane to see his mother.

“Beau Is Afraid” is like a more psychological version of NYC-born Aster’s previous works, “Midsommar” (2019) and “Hereditary” (2018), which are more obviously horror films. Aster’s work has always had an anthropological element. “Hereditary,” spoiler alert, was a study of a secret coven of witches. “Midsommar” (2019) turned its eye on folk horror, concerning a cult of nature worshipers.

“Beau Is Afraid” is a more manic-depressive “Bardo.” Beau is some variation of his creator (and the actor playing him). Unlike previous men Phoenix has played, Beau has thinning gray hair and a dad body. His mental symptoms may be the result of a new drug his therapist has prescribed. Eventually, Beau ends up in the suburbs, where he is bedridden and cared for Grace (Amy Ryan) and Roger (Nathan Lane), a surgeon. They lost a son in Afghanistan. His fellow soldier Steven lives in a trailer outside Grace and Roger’s home and due to PTSD has murderous fits.

Beau has been told that he must get to his mother’s home in time for an important event. Beau is driven by guilt. He clutches a figurine of a mother and child. He has flashbacks in which he recalls growing up with his sexy, inappropriate mother Mona (Zoe Lister-Jones). If you thought young Sammy Fabelman and young Alexander Portnoy (and middle-aged Tony Soprano) had their, ahem, hands full, think again. Yes, “Beau Is Afraid” is a psychological horror film about Jewish (and Italian) sons and their mothers. Mona is a nagging, emasculating, guilt-wielding mother in the style of Sophie Portnoy. Above all, Mona is bitter about how her life turned out, and, yes, since this is an Aster film the plot will involve head trauma.

At about 3 hours, “Beau Is Afraid” is often self-indulgent and overwrought. A side-trip into a dark wood out of Dante’s “Inferno” and an encounter with a group of traveling actors could have probably been cut, (although it will no doubt be extended in the “director’s cut” that I see coming).

In addition to sources already mentioned, “Beau Is Afraid” conjures up William Faulkner, Akira Kurosawa, “Psycho,” “Star Wars,” “Poltergeist,” even and “Stormship Troopers.” We are all “orphans of the forest,” the name the Shakespeare-quoting, traveling actors have given themselves.

The film offers Phoenix a tour-de-force role, playing hyper-distraught Beau at different stages in his life, and the Academy Award-winning actor makes the most of it, although Beau in the end is too much of a whiner and a weakling. A great Patty Lupone is a real-life witch as the older Mona. Parker Posey almost steals the film as the grown-up, sexually rampant version of a girl Beau had a crush on. When we aren’t listening to Bread’s “Everything I Own” or George Harrison’s “Isn’t It a Pity,” we hear the whistling flutes of composer Bobby Krlic aka The Haxan Cloak (“Midsommar”). “Beau Is Afraid” has comical moments. But Aster is our prince of darkness. Don’t go in the attic, Beau.

(“Beau Is Afraid” contains graphic nudity, sexually suggestive scenes, profanity and violence)