Colin Meloy, singer-guitarist and songwriting captain of The Decemberists, is a master of improbable juxtaposition: arcane, detailed fictions of star-crossed passion and avenging bloodshed dressed up in indie-rock jangle, la-de-da choruses and vintage prog-rock bombast. It should all be too much of too many good things, sinking under the weight of Meloy’s literate ambitions and heavy love of The Smiths.

But the most striking thing about the Decemberists’ wonderful July 16th show at Summerstage, under a thin, white crescent moon in New York’s Central Park, was the easy, natural buoyance with which Meloy and the band – bassist Nate Query, drummer John Moen and mini-orchestras Jenny Conlee (keyboards, etc.) and Chris Funk (a small world of stringed instruments) – told his stories. There was plenty of Ray Davies to go along with the Morrissey and John Cheever in the bleak, sexual surrender and Victorian-dancehall bounce of “Billy Liar,” from 2003’s Her Majesty. And Meloy clearly relished his guitar-hero moment in the Chaucer-Raymond Chandler cocktail “The Perfect Crime #2″ from The Crane Wife, strutting to the front of the stage to wig out in electric fuzz while the band rolled behind him like Steely Dan in getaway gear.

Hewing to a tight curfew, the usually talkative Meloy – who looked like a New Wave professor on holiday, in sneakers and a seersucker suit – kept the chatter to a remarkable minimum in order to play maximum music. He couldn’t help playing the literary-theme card, opening with a hat trick of songs about the season: “July, July!” (from 2002’s Castaways and Cutouts), “Billy Liar” (basically summer vacation gone all wrong) and the gentle drowning, in love and water, of The Crane Wife’s “Summersong.” The encore was almost half as long as the actual set, going all the way back to “Oceanside,” on the Decemberists’ 2001 EP debut, 5 Songs, and closing with a full telling of Picaresque’s whale tale, “The Mariner’s Revenge Song,” complete with typical low-budget Decemberist visuals (Funk running across the front of the stage, moving his arms like a whale’s jaws).

Yet the theatrical heart of the set – the power-opera sequence of “The Crane Wife #3″ and the three-part murder story “The Island” – was how the Decemberists truly rocked in a dazzling variety of languages: dusky, olde-English strum, heavy R.E.M.-guitar clang, climactic Who’s Next power chords, ferocious chopped-Yes rhythm breaks. Meloy’s melodies and lyrics define the elevated character of the Decemberists. But it is the band’s colorful and explosive execution that makes his songwriting much more than impressive libretto. And it sounded especially fine in the cool, clear night air, like Shakespeare in the Park – with amplifiers.