Insp. Monroe is skeptical but cautious when a young woman, Emma Crawford, rings Sun Hill and says she thinks her boyfriend may have hidden a bomb in the station. At Emma's flat, Ackland and Stamp find bomb-making equipment and a faxed warning due to be sent on a timer. PC Carver discovers a suspiscious paint can hidden in the ceiling - enough to trigger the evacuation of the station and the calling in of the Bomb Squad. The suspect, Ben Wallace, has been in trouble with the police before, and he is apprehended by DCI Meadows when he returns to the flat. As the Squad begin defusing the bomb, Ackland and Stamp visit Ben's parents whom he despises. The bomb is dismantled and the station declared safe, but Ackland and Stamp watch in horror as Ben's father is killed by a car bomb planted by his son.

Page and Hayward attend a disturbance at a pub and find the landlord and one of his regulars being beaten up by three masked men. Meanwhile, Stamp, Quinnan and Klein attend the scene of a second beating, another three masked men attacking local villain Frank McBride outside the back of his club. Realising the incidents could be connected, Hayward investigates, and discovers a turf war between two rival gangs of cigarette smugglers. As the evidence against the two rival firms stacks up, Klein finds himself in trouble when he tries to buy a mixing desk from his favourite DJ, Johnny Margolis, and ends up abducted by the McBride gang, but a freak accident leaves Tony McBride dead and Klein seriously injured.

After noting Klein missing from morning parade, Quinnan and Stamp find him unconscious and badly injured in the back of the crashed van belonging to the now-deceased Tony McBride and his cigarette smuggling gang. With McAllister determined to prove that Klein is corrupt, Boyden and the relief race to find evidence to clear his name. As Klein continues to recover in hospital, Hayward suspects that missing DJ Johnny Margolis may seem to be the key to the whole mystery, and he is found trying to escape from three thugs. Boyden searches McBride's house, and an obbo is soon set up to catch the cigarette smugglers red-handed. Boyden is stunned when he works out who is responsible for the smuggling ring.