“I tend to specialize in creepy,” says composer Tom Baker to his singers at the start of a rehearsal for his new opera-in-progress for soprano, mezzo-soprano, and electronics. But it’s not at first, as Natalie Lerch and Gretchen Conrad dialogue coolly in floating recitative—their subject: plastic surgery—over an iPad-controlled soundscape of hypnotically repeated two-note motives. That is, not until Conrad asks to have wings literally attached to her body (“stretching flaps of torso fat to fashion gliders piped with rib bone,” as Lerch’s doctor later explains). As Conrad’s character begins to dream of flying, her vocal line, until now earthbound on middle C, lifts off, arcing upward. It’s the dark side of a musical metaphor composers have used for centuries; a rising melodic line to symbolize transcendence, the supernal, here turns ominous, man playing God. “Wings” is the first act of Holos, Baker’s projected cycle of six mini-operas on themes of human transformation, and it’s the centerpiece of this Friday’s concert, a commemoration of his 20 years in Seattle with an evening of new work. His compositional preoccupations—improvisation, fretless guitar, working with dancers, and darkly intense chamber opera, among much else—will be in evidence; collaborators include dancer/filmmaker Corrie Befort, Baker’s experimental trio Triptet, and others. PONCHO Concert Hall, Cornish College of the Arts, 710 E. Roy St., 800-838-3006, cornish.edu. $10–$20. 8 p.m. Fri., April 12.