“You have knocked upon a door. A locked door must be answered, but you know not what you do…” So comes the spooky voice note that dropped into K!’s emails while trying to track down Zetra. It shouldn’t be a surprise – the duo’s mystery precedes them. Onstage, the pair look like black metal meets Blade Runner, clad in cloaks, corpse paint and chains, flanked by stacks of TV monitors displaying bizarre visuals. Between them, a guitar, a keyboard and an old Atari sequencer, they sound like Type O Negative gone synth-pop, a goth Pet Shop Boys with deliciously heavy, dark riffs. We have no idea who they are. “You seek answers from beyond,” continues the message, “but find only acolytes.” One such devotee, Gabe Franco of U.S. goth metallers Unto...