‘Sing’ is a rock ’n’ roll love story

John Carney, writer and director of “Once,” the little Irish movie that could, and did — and then did again as a hit stage musical — is back at the top of his game with the coming-of-age charmer, “Sing Street.”

Set in Dublin in the mid-1980s, a time of economic and cultural recession in Ireland (the roar of the Celtic Tiger was still a decade away), Carney’s scrappy tale of hardship, heartbreak and the succor of a good song follows Conor Lalor (Ferdia Walsh-Peelo), whose comfortable teenage life has just been upended.

His father (Aidan Gillen) and mother (Maria Doyle Kennedy) are heading for a rocky divorce, there are money problems, and Conor, 14 and shy, is being yanked from the fancy school his parents can no longer afford. Instead, he is off to a rough-and-tumble Catholic school for boys where the head master enforces the rules with a scowl and a fist, and where Conor’s fellow students treat him with indifference, or sometimes with merciless pummeling.

But something happens when Conor spies the beautiful Raphina (Lucy Boynton) out on the street, with her big hair, big earrings and big blue eyes. He boldly approaches, trying to impress this older woman (all of 17, maybe?), comically affecting a casual cool as he lets her know about the rock band he’s in, and how he’s going to shoot a music video and needs a model to star. Would she be interested?

When she says maybe, he’s compelled to dash away and actually write a song and find a band to record it, too. “Sing Street” — the movie, and the name of the hastily assembled outfit of pimply misfits — is off and running.

Walsh-Peelo is terrific as Conor, who reinvents himself as Cosmo, donning black eyeliner and androgynous getups and cribbing from Duran Duran for the look and sound of that first song. His songwriting partner, McCartney to his Lennon, is Eamon (Mark McKenna), a studious schoolmate who actually knows his way around an instrument or two.

With sage counsel from Conor’s weed-smoking older brother Duncan (Jack Reynor, doing an Irish Seth Rogen thing), the duo attentively play the latest discs from the Cure, Joe Jackson, Hall and Oates, and other essential ’80s hitmakers, crafting ballads and dance-hall ditties. The influences are transparent, the words adolescent, but it’s also undeniably catchy, fun. Gary Clark, front man for the ’80s Brit band Danny Wilson (“Mary’s Prayer”), wrote the tunes that Conor and his buddies perform.

Carney understands how music not only provides a soundtrack for a life, but can change a life, too.

It’s pretty much impossible not to love “Sing Street’s” young hero as he stumbles around Dublin, dumbstruck and smitten, at turns clueless and confident. Raphina is his dream girl, but what happens when the dreamer awakens?

In “Sing Street,” he writes a new song, that’s what.