Sting has always followed his own muse, swirling jazz, world and classical music into his songwriting, thus making his solo work unpredictable. But Into the Labyrinth is certainly the most unexpected turn he’s taken in his long career. Here he’s chosen to explore the songs of John Dowland (1563-1626), a British composer and lutenist who Sting describes as “perhaps the first example of an archetype with which we’ve become very familiar: that of the alienated singer-songwriter.” Accompanied by Edin Karamazov on lute, whose playing is simply gorgeous, Sting embraces this technically difficult music, at times layering his voice to produce a choral effect. The melancholy melodies are dissonant and moving, and Sting’s tenor generally fits the material without the effort coming off as a stodgy period piece. (Strict traditionalists will certainly scream blasphemy — assuming they listen to it at all — but the album will most likely bring the work of Dowland to a larger audience.) The vocal lines, which bend and swoop, must have been a challenge to sing , and at times Sting struggles to hit the notes. But not often, and though eve n some of Sting’s most ardent fans will be mystified, or worse, by this indulgence, the album has its charms. Besides, it’s best — and fairest — to take the music on its own terms and forget that it’s being performed by the same guy who once wailed “Roxanne.”