When an undercover officer from the Met's Football Intelligence Unit (FIU) is found stabbed after a football game, Supt. Chandler and Ch. Insp. Morys from FIU send a Sun Hill team to infiltrate Britannia, the hooligan gang responsible, and investigate their leader, a former police sergeant named Julian ""The Nap"" Napper. DC Mickey Webb goes undercover as builder Mickey Malone with support from DS McAllister as his girlfriend and DC Riley and PC Quinnan as his workmates. Webb successfully makes contact with gang member Gary Hughes, and meets Napper when the gang travel 'up north' for a game.

DC Mickey Webb is close to infiltrating the Britannia gang, despite the suspiscions of some of its members - suspiscions which fire up when DS Debbie McAllister, posing as his girlfriend, turns up to a gang meeting overdressed and wearing Givenchy perfume. Julian Napper smells a rat and follows McAllister as she desperately tries to find a hospital to keep her cover as a nurse intact. Napper catches up with her and accuses her of being an undercover reporter - with her cover blown, McAllister returns to Sun Hill. Supt. Chandler blasts her for her stupidity, and forces her to take notes as they hear Webb taking a severe beating from Napper's thugs over his mobile phone. As DCI Meadows races to save Webb, Napper stops the beating and welcomes ""Mickey Malone"" as a full-fledged member of Britannia.