Agendas are being pushed in our faces — the Republican convention last week; the Democrats winding up Thursday. But here’s a musical with absolutely no agenda, other than to take your mind off whatever may be going on outside the Engeman Theater at Northport.

Long Island’s only year-round Equity company launched its 10th season with the East Coast regional premiere — that means not counting its 14 years on Broadway — of the jukebox musical “Mamma Mia!,” based on the disco-era hits of the Swedish band ABBA, which, but for this show, might be forgotten. The musical that had people dancing in the aisles, if not right up to its 2015 close, had folks dancing like last call was hours away at opening night of this infectious Engeman production directed and gleefully choreographed by Antoinette DiPietropolo.

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Scripted by Catherine Johnson (music and lyrics by Benny Andersson and Bjorn Ulvaeus), “Mamma Mia!” gets right to the point as fatherless bride-to-be Sophie discovers her mother’s diary describing intimate dates with three men when she was 17. (We’re already anticipating “Dancing Queen,” which doesn’t disappoint.) Sophie, confident that she’ll discern which of the three is Dad, invites each to her wedding.

Hannah Slabaugh as Sophie projects a gullible innocence that tricks her into believing she can manage this without complications. Michelle Dawson as her mom, Donna, reprises a role she understudied on Broadway and played on national tour. Her expertise comes through in convincing us of her bewilderment that these men from her past have shown up for Sophie’s wedding. And she delivers with gusto the climactic “Winner Takes It All.”

The daddy candidates are stereotypical. But get over it. As some songwriter of note once asked, “What’s wrong with silly love songs?” Without overdoing it, Frank Vlastnik plays Harry as Not Donna’s Type. Or rather, she’s not his. Jeff Williams as Bill evokes a grandfatherly tone while Sean Hayden as Sam occupies the just-right category of odds-on favorite. After the title song with Donna, all are keen on the honor of giving Sophie away, while Jacob Dickey as the groom wonders why Sophie’s fuss isn’t over him.

DT Willis’ taverna set glows with a Mediterranean vibe (lighting by Adam Honoré), while James Olmstead’s band keeps the disco beat throbbing to the pulse of urgent young love, past and present. If you don’t still get it, well, never mind.