PCs Fletcher and Gayle pursue a stolen car that has been involved in a hit-and-run incident. New DC Stevie Moss joins DCs Webb and Perkins in trying to establish the identity of the driver of the vehicle, but PC Armstrong uncovers the vital evidence.
Supt Heaton organises a press conference to appeal for help in the search for an abducted 11-year-old. When a ransom note is received, DI Manson solicits the continued assistance of a convicted child killer.
Sgt Smith interviews the car-jacker involved in the hit-and-run incident. Key witness Alisha Danniels is now too scared to testify. PCs Keane and Roberts interview the car owner, and uncover details of arms dealers on the Jasmine Allen estate.
When a witness drops out of the Carly Samuels murder trial, Sgt Smith tries to persuade her best friend to testify. PCs Roberts and Noble arrest a man for arranging a brutal assault on his pregnant girlfriend.
Sgt Smith is driving the key prosecution witness in the Carly Samuels murder trial when they are run off the road. An investigation into that incident leads to vital new evidence and a dramatic courtroom confession. Rioting breaks out on the Jasmine Allen estate, with PCs Green and Hollis trapped in the mobile police unit.
Inspector Gold is determined to crack down on a surge on hoax calls. Sgt Stone and PC Stamp are pelted with eggs when they respond to one hoax call, and hit with water balloons when they attend the reported sighting of a body in the river. Sgt Wright deals with a call from a boy who claims to have been kidnapped by his father.
PCs Armstrong and Gayle stop a 12-year-old boy driving a stolen car, and investigate claims that the boy's father is being threatened by a known violent offender. DCs Moss and Perkins investigate the provenance of an explicit DVD featuring a local celebrity.
PCs Fletcher and Armstrong tend to the victim of an apparent assault. PC Gayle gets emotionally invested when investigating a serious assault on a twelve-year-old boy, and becomes the subject of a DPS investigation.
Sgt Stone and PC Armstrong investigate an assault on a young woman found in an alleyway outside a club. The officers suspect rape, but the victim insists that she was the victim of a mugging. A drugs raid planned by DS Carter and DCs Moss and Perkins is a bust as they were fed false intelligence.
PCs Valentine and Green respond to the reported sighting of a body being thrown into the river. DS Carter leads an investigation into the murder of a doctor, recently exonerated after allegations of professional negligence.
Supt Heaton decides to go out on the beat with PCs Green and Keane, who are both suffering after a late night out. Insp Gold and Sgt Wright decide to keep an eye on them. PCs Valentine and Roberts investigate the theft of some electrical goods from a delivery truck.
PCs Fletcher, Gayle and Armstrong, and Sgt Stone, are called to a disturbance at a nightclub. Armstrong comes to the aid of undercover police officer Andrew Tipping. DC Masters deals with a man who is determine to find the drug dealer he blames for his daughter's death.
PCs Stamp and Gayle find the body of a missing teenager in a derelict house. DS Turner and DC Moss investigate and discover the girl was hooked on heroin and forced into prostitution by a local drug dealer and pimp.
Sgt Stone and PC Fletcher arrest Danny Peters for the attack on DS Turner. Turner is devastated to discover that the needle might have been infected with the HIV virus. DC Moss goes undercover as a heroin addict to investigate a major heroin smuggling operation.
Sgt Smith and PC Fletcher come to the aid of Johnnie Jackson, a former East End gangster who has been badly beaten. Smith and DS Carter discover that Jackson's grandson is dealing drugs on behalf of his illegitimate son, who runs a drugs and prostitution racket.
PCs Keane and Armstrong are called to a break-in, but the intruders run off, having been fought off by the householder. Armstrong and PC Stamp later come across one of the intruders, who has been badly injured. The evidence suggests that the householder may have used unreasonable force, and he is arrested for attempted murder, but Keane is convinced of his innocence.
DC Jacob Banks arrives at Sun Hill, and assists DC Webb with an investigation into the murder of a private investigator, who had been looking for a missing teenaged girl. PC Keane feels she is being singled out by Sgt Stone
PC Armstrong goes under cover at a City trading house to investigate the possible involvement of one of a group of traders in the disappearance of a missing twenty-one-year-old woman. PC Keane is frustrated that Sgt Stone nominated Armstrong for the assignment, while Keane herself has been landed with more routine work, and is delighted when she gets the opportunity to join her colleague under cover
PCs Keane and Armstrong are on the beat when they are shocked by two explosions. Sgt Stone coordinates the efforts of officers from Sun Hill and Barton Street as they deal with terrified people desperate for information, and the threat posed by opportunist criminals. When police receive a warning about a third explosive device, Keane puts her life on the line
DI Karen Lacy from the Counter Terrorism Unit takes charge of the investigation into the bombings of the day before. Sgt Stone and PC Armstrong search for the man suspected to be behind the campaign. DCs Webb and Walker search his home for clues, little suspecting that danger awaits. Tensions between Sgts Stone and Smith reach a head
Another bomb warning is sent to Sun Hill. DC Dasari interviews the men apparently targeted in the earlier incidents. As the time of the threatened explosion approaches, officers realise that the person behind the bombs has been in the station throughout the investigation. Sgt Stone and DC Webb race to find it in time. Officers attend PC Keane's funeral service..
A grumpy DI Manson returns to work determined to bring some discipline back to CID. He and DC Moss investigate the apparent disappearance of a groom on his wedding day after a burglary. Further investigation leads to a gay-bar and the chase is on to capture a Kylie Minogue impersonator!
Sgt Wright and PC Valentine come across a young assault victim. They discover that his house has been ransacked and that his father had borrowed money from a loan shark. The officers clash over how to run the case when drugs are discovered in the boy's room. DCs Masters and Moss discover that the victim's father is dealing drugs and is involved in a turf war.
DS Carter and DC Perkins are stuck in a traffic jam when they witness a stabbing. Increasing conflict between the two detectives compromises their subsequent investigation into an international car theft racket.
PCs Armstrong and Green attend to the victim of a serious assault and establish that he had been in an argument with a young runaway. DS Turner and DC Perkins talk to the victim and his wife, and discover that the girl is their daughter. The wife admits to the assault, but the officers suspect that she is covering for someone.
PC Green is called to the scene of a suspected suicide at a motorway bridge and recognises the victim as a teenage runaway. Some sex tapes lead DS Turner and DC Perkins to investigate the victim's boyfriend for her murder.
PC Valentine shows new recruits PCs Leon Taylor, Arun Ghir and Millie Brown around Sun Hill. DC Masters investigates a break-in at a hardware store. Officers are then called to a bank, which has been robbed using equipment stolen from the store
DC Banks is confronted with a volatile situation when he responds to a call about a young boy playing with a weapon. PC Mel Ryder joins the team and she and Sgt Smith are called to a break-in which leads to an investigation into a double kidnapping.
PCs Roberts and Gayle attend to a woman who was the victim of a sex attack at her home. PCs Ryder and Valentine investigate. A suspect is identified, but he claims she was a willing participant. Supt Heaton sends Sgt Smith undercover, with DC Moss posing as his girlfriend, to expose a gun running racket.
PCs Green and Fletcher arrest a teenager after a box of fireworks explodes in front of their patrol car. The fireworks are part of a consignment to be used at a forthcoming football match, where Sun Hill officers will be in attendance on crowd control duties. DI Manson mounts an observation at the stadium, as Sgt Smith is due to meet the man behind an arms smuggling operation.
Sgt Smith, working undercover for an arms dealer, meets the gang leader who is funding the latest deal and witnesses the beating of the dealer's nephew. Smith is sent alone to collect the shipment, while the gang detain DC Moss, who has been posing as Smith's girlfriend. The nephew's unexpected arrival ahead of the exchange threatens to undermine the deal and to expose Smith's cover.
DCI Meadows's God son calls to collect his father after a poker game and is knocked down in a hit-and-run incident outside the DCI's home. Meadows assumes he was the target, and clashes with DC Banks and DC Webb, who suspect that one of the DCI's friends may have been the intended target. Meadows is shocked to discover how little he knows his oldest friends.
DCs Webb and Banks investigate a suspected arson attack on the home of a man who had helped out on an observation some years before. The victim's son, his neighbor and his landlord are among the suspects, and Banks's wife, Naomi, is the landlord's solicitor.
PCs Armstrong and Gayle are called to attend when a teenage girl is knocked down in a hit-and-run incident. Sgt Stone and PC Stamp track down the owner of the vehicle, who denies responsibility. Officers discover that the key witness to the incident is a missing person who is hiding a family secret.
PCs Armstrong goes to the aid of a teacher who is being harassed by two former pupils. She and PC Stamp discover that the teacher has been having an affair with a third girl, who is now missing. PCs Ghir and Brown investigate a series of break-ins. PCs Gayle and Stamp assist with a sting operation at a local car-wash company.
Sgt Wright and PC Fletcher attend the scene when a piece of scaffolding is driven through a car, impaling the driver. Wright comforts the driver while Fletcher tries to establish whether the incident was an accident. The case leads both officers to re-evaluate their careers.
Sergeant Rachel Weston joins Sun Hill and investigates a break in at a jewellery shop with DCs Walker and Webb. PCs Ryder and Roberts attend the scene of a two-car road traffic accident. Weston and Ryder realise that the getaway vehicle was one of those involved in the accident.