Documentary maker Livvy Haydock investigates the rise of contraband inside UK prisons, and uncovers the links in the chain on both sides of the law. She spends time with criminals who are making 10 times a drug’s street value by selling to prisoners behind bars, including a ‘networker’, a key link in the chain who sources goods on the outside and gets them to whichever inmate has made an order via the mule.