Patti Cake$ Danielle Macdonald, Bridget Everett, Siddharth Dhananjay. Directed by Geremy Jasper. Rated R. Now playing in select theaters.

The title character of Patti Cake$ is not your typical rapper: Patricia Dombrowski (Danielle Macdonald) is a plus-sized white woman from suburban New Jersey who works nights as a bartender and dreams of hip-hop stardom. In her fantasies, she swaps verses with her idol, mega-star rapper O-Z, but in reality the 23-year-old lives at home with her bitter alcoholic mother Barb (Bridget Everett) and her ailing grandmother (Cathy Moriarty). Her best friend is Jheri (Siddharth Dhananjay), an Indian-American pharmacy tech whose smooth vocals complement Patti’s rapid-fire lyrics about life in working-class Bergen County.

Patti’s triumph-of-the-underdog story hits a lot of familiar beats, especially in the movie’s second half, as she teams up with an introverted musician (Mamoudou Athie) to seriously pursue her ambitions. Her mother, her musical inspiration and her co-workers dismiss her talents, but she gets one big chance at the movie’s climax to prove herself.

The outcome of that final showdown is entirely predictable, but the charismatic Macdonald (an Australian with no prior rap experience) makes Patti easy to root for, and first-time writer-director Geremy Jasper showcases plenty of authentic New Jersey grit before giving in to feel-good clichés. Patti’s music may not quite be believably brilliant (unlike the songs in obvious influences 8 Mile and Hustle & Flow), but the movie is charming enough that it doesn’t really matter.