The members of Denver's Planes Mistaken for Stars wear their beards, greasy hair and disillusioned countenances like a band that knows what "heavy" really means. The music on Mercy makes good on the promise. Thick and sweaty, with the heft of a muddy sledgehammer, the album delivers a range of emotions without sounding cheesy, even during quiet moments, which come just often enough. Songs such as "One Fucked Pony," "Keep Your Teeth" and "Killed by Killers Who Kill Each Other" triumph as fierce, guttural paeans to misery punctuated by raunchy riffs soul-baring but always rocking. Mercy is that rare metal album that wallows in misery, deriving its evil and menace from real life while remaining mature and intelligent.