Mirel Wagner begins “Oak Tree,” laying in a bed of “roots and leaves,” left there by a lover who sings her to sleep before disappearing into the night. As the song progresses, though, it’s hard to tell if Wagner is asleep, or if something graver has taken place. In the second verse, she quotes Blind Willie Johnson and sings of her soul being “free and unbound” as an eerie, far-off choir clusters in the background like fireflies. Wagner’s no stranger to darkness — her excellent first record was full of ballads that dealt with murder and the occult — but on “Oak Tree,” she’s the most melodically-confident she’s yet been. Her voice recalls PJ Harvey in “C’Mon Billy,” another song about a lover left lonesome and the dark fate that befalls her.