Serenella’s racks are to Boston shoppers what the sirens were to Odysseus: pure, unadultered temptation. Maybe it’s the thoughtfully edited assembly of Pucci brights, quivering with delicious swirls of aqua, canary yellow, and bubblegum pink. Or it could be the crisp Balenciaga skirts, the tasteful cashmere twinsets, or the Roberto Cavalli numbers that are, by turns, over the top and tame. Whatever your particular weakness, prepare to abandon all reservation when you enter. Everything here sings, and—like a siren—even when it’s loud, it’s beautiful.