It’s been four years since the indie pop shapeshifters Mr Twin Sister released a full-length record, but a recent trickle of steamy lounge cuts suggests that their dry spell is over. The New York group follow last month’s Bossa Nova-laced jam “Jaipur” with “Echo Arms,” a twirling disco trip through the galaxy. Nothing about this track is rooted in terrestrial concerns; hand drums are stretched out with a veneer of reverb, strings swell in lofty arcs, and trills of flute dart like comets to the furthest reaches of the song. Vocalist Andrea Estella enhances this sense of flotation; her whispers drift through a dense network of chirping guitar, mewling synths, and crackling hi-hats. “Echo arms round me,” she exhales, shaping the song’s only intelligible lyrics with her breathy falsetto. Estella’s delivery is so lax and seductive atop the band’s easy funk that it’s hard to know whether one should get up and dance or just dim the lights, kick back, and enjoy the ride.