Punk, lunk, drunk, skunk, hunk, monk and singer-songwriter Bill Callahan. (Chris Taylor.)

Having spent 15 years writing lo-fi outsider folk ditties as Smog, “Apocalypse” is the 44-year-old Maryland native’s fourth album under his own name. And it might be his strongest, reducing romance and urgency to absolute zero, allowing Callahan’s lyrics to exert their weird gravity without any distractions.

Both anemic and hypnotic, Callahan’s singing always borders on speech, making him sound like he’s chosen to live outside of his songs, like some disembodied narrator. But he does squeeze a few drops of melody into the album’s final moments, cryptically crooning, “DC 450.”

It’s the album’s catalog number - one more riddle for the road.