"High concept" is a term that often connotes an overwrought art project -- something self-consciously deep or, worse, "important." But when affixed to Denver's Uphollow, the description celebrates the band's ability to cultivate new ideas through sound. In 1993, founders Ian O'Dougherty and Whit Sibley released Soundtrack to an Imaginary Life, a forty-minute-long rock opera that was divided into eighteen sections. After nine cross-continental, whirlwind years -- collectively, the pair bounced from Australia to Spain, Eastern Europe and California -- Uphollow has returned to Denver and the conceptual realm. The band is currently playing behind O Peach, a ten-song narrative cycle that chronicles the lives of three characters and that relies upon the mathematical equation known as the golden ratio. Three chords and the truth this ain't. Now a fourpiece rounded out by cellist/pianist Ian William Marshall Cooke and drummer Justin Ferreira, Uphollow has found an instrumentation and lineup to match its ambitions: There's a lushness and beauty to the music that might make you forget the complication of the arrangements. The band performs Friday, November 15, at the Bluebird Theater, with Fort Collins's Monofog and Burstable, the effervescent new project from former Acrobat Down members Aaron Hobbs and Jaime White. The Bluebird staff should check the venue's power supply: The evening promises a creative surge.