The Sicilian Vespers is top-drawer Verdi that never quite caught on. The story unfolds in 13th-century Palermo, a city groaning under the yoke of French occupation. But why, people wonder, is the foreign governor Monforte putty in the hands of the fatherless local firebrand Arrigo? (Where’s ancestry.com when you need it?) The prima donna is the Sicilian noblewoman Elena, whose solos include a heaven-storming call to arms, a broken-hearted love song, and the bejeweled bolero of a bride who will not live out her wedding day. The soprano Rachel Willis-Sørensen has the requisite technical and emotional range, the flair, and the stamina for this extraordinary assignment. It’s the kind of challenge she revels in. —Matthew Gurewitsch