American PR consultant Liz Garvey is hired by Metropolitan chief constable Richard Miller to help the police force improve its image. At the same time documentary film maker Matt Coward is shadowing Territorial Support Group officers Davina, Robbie and Clarkey as they arrive at a not very well-organized Kurdish protest march where Robbie has to remember he is being filmed and tone down the abuse. Elsewhere Officer Warwick accidentally apprehends an innocent mother whom he has erroneously suspected of being a drug addict. Liz's introductory speech is interrupted by news that a sniper is randomly shooting people around the capital and her disgruntled assistant Finn, annoyed at being passed over for promotion, deliberately makes her look stupid at a press conference by withholding information - as a result of which he is almost sacked. Liz discovers that the sniper is an embittered divorcee who is posting messages on Twitter, from which she locates where he is hiding. The TSG dump Matt ...