Annie Clark, a.k.a. St. Vincent, used to be affiliated with The Polyphonic Spree, which might suggest pop music of a peculiarly sunny and charged sort. But St. Vincent eschews bombast for something that leans closer to Kate Bush, David Bowie, and Dirty Projectors. The internal struggle within Clark’s work has always been beauty vs. beast. On her sophomore effort, Actor, that was embodied by the digital smears and orchestral eeriness from producer John Congleton as much as the roar of Clark’s guitar. Congleton returns for St. Vincent’s third LP, Strange Mercy, where the angel-voiced Clark once more goes toe-to-toe with ugliness—and even purges some from within. Strange Mercy does for the arc of Clark’s career what Black Swan did for Natalie Portman’s: Engaging the darkness (rather than just acknowledging it) adds some flesh-and-blood humanity to an artist whose excellent output has nonetheless been marked by cold distance.