This episode opens with a young man accidentally dropping a large quantity of cocaine from his jacket pocket outside a petrol station - all caught on CCTV.On the case are hard-bitten Detective Constable Colin Knight and fresh-faced Police Constable Oly Tomlinson, who joined the team three months earlier. They get off to a promising start, tracking down the owner of the vehicle the passenger was travelling in.DC Knight brings in his chief suspect for questioning and discovers that, just like the man in the CCTV footage, he has a striking tattoo on the right side of his neck, but could it be a case of mistaken identity?Also brought in to the custody suite is Darren, a man arrested on suspicion of theft of meat from Marks & Spencer.As he is booked into custody it soon becomes apparent he is a heroin addict. Sympathetic Custody Sergeant Pete Fitz-Gibbon tries his best to persuade him to stay strong and get clean.Both cases provide a stark picture about the dark world of young people caught up in a cycle of drug addiction and crime in Luton and the challenges facing the police as they tackle it.