At midnight on Friday night, Mt. Wolf brought us a legitimate lullaby for our South X Lullaby series. Singing its single "Hex" while sprawled across the bed in Bob Boilen's hotel room, the British band made the otherwise anonymous space intimately personal. Sebastian Fox's delicate falsetto rests on a lush and light arrangement of chiming 12-string guitar, harmonies and brushwork. It's emotionally intense — but, as with any lullaby, never past the threshold where the neighbors come knocking.