Hood Natured: Grayceon lets its prog rev up organically.

Though San Francisco’s Grayceon sounds nothing like Dream Theater or Mastodon, it wouldn’t sound too out of place on a bill with either band: The trio combines prog’s obsession with long-form composition and unconventional orchestration with metal’s crunchy guitars and hyperactive drumming. On its sophomore album, This Grand Show, the group’s unusual attack meshes beautifully, thanks in large part to electric cellist Jackie Perez Gratz, who can just as easily play lyrically or blast out chunky riffs. The album’s best moments, particularly the opening track, “It Begins, and So It Ends,” connect her patient melodies with guitarist Max Doyle’s aggressive riffing and by Zack Farwell’s powerful drums. Though the disc amply showcases all three musicians’ skills, there are no real solos to speak of—a self-effacing strategy preserved from Grayceon’s 2007 self-titled debut. And they still have the ambition to tackle long-form compositions. Three of the five songs on This Grand Show comprise all but 10 minutes of its 55-minute run time, and its 20-minute centerpiece, “Sleep,” gives the group a chance to show off some new tricks. About eight minutes in, the music halts, and the trio abandons its usual metal-inspired bombast, launching into a lengthy psychedelic workout. Doyle picks out forlorn-sounding, reverb-laden notes that recall the trippy middle section of Pink Floyd’s “Echoes,” providing a calming eye in the song’s otherwise turbulent storm. So when the big riff returns at song’s end, the song is all the more effective. That flexibility, unfortunately, doesn’t extend to the vocals: Perez Gratz and Doyle’s harmonies can’t compete with their titanic instrument work, though that’s easy to overlook on “Love Is,” whose frequent loud-quiet shifts feel effortless and natural. At their best, Grayceon’s songs have all the elegant, inexorable strength of a tide rolling in. If they add in a singer worthy of their music, they should have no problem stretching their ambitions even further.