Image Credit: Doug Hyun/HBOAnother spectacularly bloody, true-death-gooey season of fangs, flesh, and fairies came to an end last night, and—no spoiler alerts!—EW spoke with the show’s music supervisor, Gary Calamar, to get the backstory behind their rerecording of the classic blues song for which the finale episode was named.

Calamar, who also handles all the music for Dexter, House, and Men of a Certain Age, as well as holding a long-running DJ spot on LA indie station KCRW, tells EW of covering Howlin’ Wolf’s iconic song “Evil (Is Going On)” with CC Adcock and“Bad Things” singer Jace Everett: “We were looking for a sort of signature song, and we wanted to have our own. We love Howlin’ Wolf, but we just wanted to have something a little fresher, something exclusive.”

Indeed, Everett and Adcock’s version features a few unexpected guests: Calamar’s own eight-year-old daughter and two friends, including the young daughter of Say Anything actress Ione Skye, who is also stepdaughter to Australian musician Ben Lee. (The girls may sing on the song, but don’t worry; they aren’t allowed to watch the show.)

Stream the track—also found on the show’s second-volume soundtrack, released in May—after the jump:

Says Calamar of the vetting process for each episode, “I get the [True Blood] scripts early on, so I read it and get some idea of where the music is going to go. Sometimes the writers will write in a particular song, and sometimes we can get them rights for that, and then we have a spotting session with [show creator] Alan Ball, the composer, and various editors.”

For all the show’s heavy Louisian-ity, Calamar does have a little leeway, musically: “We do have [vampire hangout] Fangtasia,” he continues, “where we play more industrial, darker stuff, then music for Sookie and Lafayette, which kind of opens it up a little bit. It’s great because Alan is such a fan, and gives us a budget to play with.”

Certain songs, of course, are out of reach of even the biggest stack of cable-network cash: “Led Zeppelin is still very tough, Bruce Springsteen, the Beatles. Everyone always wants that stuff—they’ll put it right in the script—and you have to break it to them,” he says with a laugh.