For outlaw motorcycle gangs, tattoos prove dedication and mark alliances. The bikers who wear them live by their own set of rules. Marked goes inside the clubhouses of three of these underground organisations to examine how ink separates these riders from the pack. Witness rituals never before seen on television, as members get permanently branded with tattoos rife with dark, devilish iconography. The engines roar as we decode the hidden meanings of some of the most popular biker images and learn what it takes to live the rough and tumble biker lifestyle.