Apparently John Carney has one basic story to tell—the old chestnut about the power of music to change lives for the better. It’s a message he’s conveyed in his previous two films, “Once” and “Begin Again,” and it’s repeated in his third, “Sing Street.” But if the narrative hits familiar notes, Carney has a knack for presenting it in a way that makes it feel fresh, so that you probably won’t mind the repetition; in fact, you’re likely to enjoy it.

This time the story is set in Dublin in the mid-eighties, and centers on Conor (Ferdia Walsh-Peelo), a fifteen-year old with problems at both home and school. His bickering parents Robert and Penny (Aiden Gillen and Maria Doyle Kennedy) are in financial straits, and to save money they remove him from his high-toned Jesuit school and send him to a far rougher one run by the Christian Brothers. The transition is no fun: he’s bullied not only by brutish classmate Barry (Ian Kenny), but by the principal, stern Brother Baxter (Don Wycherley), who humiliates him for not wearing the dress-code black shoes.

Conor finds a pint-sized pal in Darren (Ben Carolan), but more importantly he works up the courage to approach Raphina (Lucy Boynton), a beautiful girl a bit older than he whom he spies standing on the steps across the street from the school. She aspires to go to London and become a model—and in fact is planning to do just that with her boyfriend—but he piques her interest by telling her that he’s lead singer in a band and would like to feature her in their next video. She shows mild interest, but to take things any further Conor, who’s done little more than fiddle around with his guitar, will need to assemble a band and find music for it to play and tape for her to listen to.

Darren, an aspiring promoter, steps into the breach and enlists his friend Eamon (Mark McKenna), who can play almost any instrument (and has a thing about his pet rabbits). Then they add Ngig (Percy Chamburuka) as keyboardist and eager Larry (Conor Hamilton) and Garry (Karl Rice) on drum and bass. All they need now is music, and for that Conor turns to his brother Brendan (Jack Reynor), a shaggy-haired college dropout with a sizable collection of LPs, an encyclopedic knowledge of rock and a willingness to act as an advisor to his little bro. The group—named Sing Street after the address of their school on Synge Street, begin by playing songs by the name bands of the time (Duran Duran is a particular favorite), but Brendan convinces them that original material is a must, so Conor and Eamon, joining forces to provide words and music, come up with a catchy number called “The Riddle of the Model,” and a suitably impressed Raphina agrees to star in their absurdly low-tech video of it. Other tunes will follow.

From this point the plot trajectory is not difficult to predict. Conor will increasingly fall for Raphina, though her London plans are always threatening to take her away. Meanwhile he and his buddies will create a succession of amusingly period-appropriate tunes (actually written by Carney and Gary Clark) that culminate at a school dance which Conor imagines as “Back to the Future”-style shindig where his dreams come true. And, after a fashion, they do (although, considering the ages of the principals, one might have some misgivings about how).

Gawky, open-faced Walsh-Peelo makes a likable young protagonist, and Boynton an ingratiating object of his affection. They’re surrounded by adept scene stealers—among the members of the band, McKenna and Carolan stand out, but even they’re surpassed by Reynor, whose slacker demeanor is bound to prove a crowd-pleaser. The production is hardly sumptuous, but Yaron Orbach’s cinematography takes advantage of not only the locations but the eighties detail in Alan MacDonald’s production design, Tamara Conboy’s set decoration and Tiziana Corvisieri’s costumes while taking on a cheerfully amateur look in the videos supposedly contrived by the boys.

Ultimately, though, it’s the music that counts—for the movie as much as for Conor. “Sing Street” doesn’t have the nuance of “Once,” which is still Carney’s best film by a long shot. But it’s an agreeable complement to it.