"Sister" was recorded at Studio Cobra in Stockholm, Sweden during March 2013. The album was produced and mixed by Martin "Konie" Ehrencrona and stands as a logical next step above and beyond its predecessor, "The World.The Flesh.The Devil." In Solitude's strength resides in their ability to craft dark and oppressive atmospheres within the auditory realm of classic heavy metal. "Sister" compounds this trademark sound further, beginning with the acoustic intro, "He Comes," and saturates the record in an aura of uniqueness; see: Lavender" and the title track. The album concludes with an 8-minute, driving, near trance-like opus that features guest guitarist Pelle Forsberg (Watain). Additionally, Jarboe of Swans fame can be heard on "Horses in the Ground." Moods range from Mercyful Fate-esque guitar flavors, shadows of Black Sabbath, the heavy dissonance of Swans, to straight-forward, ear worm riffs. In any case, one thing can be said for certain: their delivery is as genuine as it is impressive.