“Foreigner,” the opening track of Pallbearer’s 2012 debut Sorrow & Extinction, is the best song about the uncertainty of embarking into unknown lands on a mission of extraordinary importance since Led Zeppelin’s “No Quarter.” In roughly 12 minutes, the Arkansas doom-metal quartet tells an expansive and heroic tale about crossing into potentially hostile and uninviting territory. The song starts with soft but stalwart acoustic-guitar lines that evolve into dense electric Sabbath sludge as our protagonist confronts extreme darkness, and his fear of becoming a conduit for the Ancients. (I don’t even know what this means, but it’s compelling and gorgeous.) “Lost within the shade, I call out for a helping hand,” sings Brett Campbell during the seat-grippingly vivid finale. Will the towering beings that haunt him now help him? What’s even happening here? I dunno. Go ask Campbell after the show. 

Wed., Jan. 30, 8 p.m., $16, with Enslaved, Royal Thunder and Ancient Wisdom, Underground Arts, 1200 Callowhill St., 215-624-5765, undergroundarts.org.