This summer we loved to get “2 On” with Tinashe, but the rising R n’ B star’s new single “Bet” takes her firmly out of the club and into darker territory. The track is the latest taster of her upcoming debut album Aquarius, out next Tuesday, and shows a return to the murkier sounds of her excellent 2013 mixtape Black Water. Menacing, subterranean production from DJ Dahi and Blood Diamonds underscore a rawer side to Tinashe’s voice. As she stretches out the syllables of “Cali-for-nia” over cavernous breakbeats and twisted vocal samples, we experience a new Tinashe: hurt, longing, and in love. But what’s most exciting about “Bet” is its ingenious fluidity. The production maneuvers from Clams Casino-esque bass to a caterwauling guitar solo from Devonté Hynes, while Tinashe shifts from full-on melisma to intimate whispered rap with ease. If the rest of the album sounds as futuristic as this, this fall will certainly be the Age of Aquarius.