Returning for its second series on BBC1, it offers offering an honest account of life inside the custody suite at the headquarters of Humberside Police. Each film focuses on an individual custody sergeant, the man in charge of each shift and responsible for the wellbeing of up to 15 detainees and a team of detention officers. A detainee who's just overdosed on heroin is Sgt Grunner's first challenge in this week's episode of The Lock-Up. The man is a regular visitor to Humberside Police Headquarters' custody suite, and this time he loses consciousness in his cell.