The upcoming horror film The Retaliators’ theme song, “21 Bullets,” features Mötley Crüe. The band’s bassist Nikki Sixx co-wrote “21 Bullets” with his Sixx: A.M. bandmate James Michael. In addition to Mötley Crüe, the track also features guest appearances by several hard rock acts, including members of Asking Alexandria, Ice Nine Kills and From Ashes…