This police drama follows the activities in and around Sun Hill, a police station located in the fictional East London borough of Canley. The focus is not just the gritty reality of police work, however; the lives and loves of the officers who staff the precinct get equal play.
A dying convict accuses Jack Meadows of a frame-up more than 20 years ago, and DI Neil Manson is brought in to investigate his old boss.
DI Neil Manson catches up with Jack Meadows, and in a moment of weakness gives him 24 hours to clear his name.
Lewis Hardy gets his first taste of undercover work when Okaro organises a drugs bust on a notorious estate, while Terry Perkins tackles a gunman.
Ramani gets a taste for street-level action when she helps Phil and Terry track down a machine gun-wielding shop raider.
Uniform branch give CID a lead on a major drugs baron, but Smithy's satisfying day takes a vicious turn when he sets out to meet Louise.
Smithy wakes up to a living nightmare as he is booked for drink-driving and interrogated on suspicion of killing Louise.
Smithy puts on a brave face for his court hearing, but CID's efforts to link Pete Larson with Louise's death come unstuck when they let a gang member slip through the net.
DCI Caddick of the Child Abuse Investigation Team is impressed by Ramani's ability to build links with the immigrant community, and Phil Hunter reaches a crossroads.
Zain crosses DCI Keane's path once too often as he mounts a lone crusade to save Smithy from the frame-up by Pete Larson. Ramani gets a surprise job offer.
Lewis witnesses a shooting at his cousin's engagement party, and soon finds his family loyalties at odds with his professional obligations.
The rival gang leaders are arrested on their way to a showdown, but not before Lewis has been held at gunpoint by his cousin's friend.
A frantic father agrees to hold a press conference appealing for news of his missing seven-year-old daughter. Phil Hunter contemplates life without Cindy.
Pressure mounts on James Tennant as his story fails to add up, and he vents his frustrations on family liaison officer Suzie Sim.
Zain makes a high-risk decision to broker a deal with gang member Jordan Tomlin in a bid to end the violence once and for all.
Zain's devious deal with gang member Jordan Tomlin backfires when a CID sting delivers only two of the promised eight automatic weapons.
Gina returns from Australia, and a prison visit finds Dale Smith in the depths of despair.
Emma Keane and Leela Kapoor are at a DJ competition when gunshots ring out - and both Zain Nadir and Lewis Hardy have their own reasons for feeling guilty.
Smithy crosses swords with the Longmarsh heavies and takes a beating, but it is the approach of Louise's funeral that drives him to the point of despair.
Smithy is refused permission to attend Louise's funeral, and flips when a fellow inmate sets fire to a photograph of her.
Following the death of Jordan Tomlin, the Sun Hill team arrive to police a sell-out gig at the Bombastic nightclub - but the plan goes awry.
The nightclub disaster sends shock waves through the Sun Hill relief, with Will Fletcher and Emma Keane worst affected in the traumatic aftermath.
Leela finds herself up against Honey in the election for Federation representative, and a newcomer is offered promotion ahead of Suzie.
Suzie is so busy working for her sergeant's exams she doesn't know the position at Sun Hill has already been taken.
Smithy reports for duty at Sun Hill, but is taken aback to discover he's assigned to investigate a crime involving former cellmate Morris Leatherhead.
Nadir and Perkins are pleased when DS Turner allows them to bend the rules - but is it just a case of mistaken identity?
Hunter investigates the attack on his brother. Meanwhile, a hit-and-run leaves a girl dead and Stamp is forced to arrest an old friend who may have been behind the wheel.
Hemmingway and Harman deal with an arson attack on an elderly man's home, and Bryant is outraged to hear that her son Liam may be involved.
CID set up a phone line to trap a man who claims to have a missing child.
June Ackland and PC Roger Valentine watch in horror as PC Lewis Hardy risks his life to save someone trapped in a burning building.
Webb realises that he knows the parents of two missing sisters, when Smithy conducts a briefing which has links to the Amy Tennant case.
Questioned by Sim, an 11-year-old girl admits to beating her younger sister who is fighting for her life in intensive care.
Following an attack on Robert Willis, the team search for a cab driver who Valentine falsely claims is a witness.
A man is arrested for criminal damage by probationary PCs Lewis Hardy and Emma Keane, but Gina Gold has to take over the interview when he confesses to murder.
A new initiative brought in by Okaro to reduce car crime uncovers a scam where cars are being stolen to order, abandoned, and then picked up by a scrap metal dealer.
A working relationship develops into much more for Sam and Stuart, while Zain continues to ignore the rule book during investigations into a fake perfume operation.
A local celebrity is questioned over allegations of intimidation against a rival bar owner and Mickey Webb spends time with a battered wife.
Mickey arrests a friend for killing her husband, but risks disciplinary action by urging her to plead self-defence. Gina plots to save Laura's career.
Terry poses as a hitman to entrap a gambling shack owner trying to dispose of his wife's lover. Roger is furious with Lewis when the pair lose track of a prisoner.
Fletcher and Keane come across a frightened toddler with someone else's blood on him, who eventually leads them to where his parents abandoned him.
Feelings run high in the community when a 12-year-old suffers gunshot wounds, but refuses to say who is responsible. Lewis puts Roger in a difficult situation.
Adam finds his reaction to the furore over the shooting incident could jeopardise his application for promotion, and trainee DC Kezia Walker finds a kindred spirit.
Sun Hill bids farewell to senior officer Adam Okaro and speculation begins over his successor's identity. Roger Valentine's wife files for divorce.
New Superintendent John Heaton sets a cracking pace in the operation to find drug dealer Tom Dwyer, but Stuart and Phil are preoccupied with affairs of the heart.
The new man in Yvonne's life thinks she's a nurse - until her work makes front page news in the local paper. Mickey's relationship with Mia reaches crisis point.
Phil urges caution as Zain continues to bend the rules during an investigation, and John Heaton makes his mark on Sun Hill with a solo arrest.
James Tennant claims to have a new lead in the search for his daughter. A rape victim comes to the station and identifies Tony Stamp as her attacker.
A failed decoy operation to find the serial rapist puts Sun Hill back to square one, but PC Tony Stamp uses his cabbie connections to nab the prime suspect.
Terry and Mickey investigate an armed robbery on a shop, and Matt Hinckley's arrival as CPS lawyer at Sun Hill prompts further heart-searching for Emma and Will.
Heaton's zero tolerance policy on drugs causes tensions within his staff, but provides an unexpected lead. A vandalism case poses a moral dilemma for Will and Dan.
Roger Valentine returns to work and proves to be a bit heavy-handed dealing with a stalker. Zain gets a lucky break in his inquiries.
When Terry's daughter is found to be involved in the local drugs scene, he goes undercover to find the dealer, but is foiled by Zain's off-the-record activities.
John Heaton gives his backing when he learns of Zain's undercover operation to gather evidence - not realising his detective is sleeping with the enemy.
Kezia Walker is furious when the case against rapist Keith Durante is withdrawn on a technicality, and resolves to put pressure on the suspect's wife to admit he was lying.
Kezia and Smithy work together on a courier van hijack and soon get a result, but later find themselves in trouble for needlessly scaring one of Keith Durante's rape victims.
Lewis plays midwife to a road accident victim who goes into labour, while Roger searches her car and discovers a large haul of cocaine.
Will Fletcher goes undercover to investigate a secret organisation of racist thugs and is shocked to discover his boxing pal Euan Thomas is involved.
As Heaton and Meadows argue about using an inexperienced officer in undercover surveillance, Will is lured into a trap.
Les Dennis guest stars as a frantic son whose 75-year-old father has gone missing. Meanwhile, Terry is made a fool of, and Lewis ignores warnings to stay away from Holly.
Samantha questions a woman whose infant son has ingested heroin, while Zain tells Neil they cannot arrest Kristen as there are bigger fish to fry.
DC Walker and DC Nadir investigate a suspicious fire at a clothing warehouse. Meanwhile, a transgender woman facing harassment receives help from PC Valentine.
Nadir comes up with a story as to why he was at the club when Louis Drake was attacked.
A former armed robber is stabbed on his release from Longmarsh.
During a raid, the team discover an elderly lady having a heart attack. Meanwhile, Nixon has a miscarriage.
Gold is surprised to see Okaro at Sun Hill, and wants to see Heaton about the bad press after Janet Fenton's death.
A fire in a B&B alerts the Sun Hill watch to an illegal immigration operation on their patch. Stalker Keith Durante is finally brought in for questioning.
A dog-napping enquiry turns into a murder investigation, PC Tony Stamp's father has a heart attack, and PC Will Fletcher returns to a warm welcome from the team.
Casper and Fletcher find a man unconscious in the street and discover that he's overdosed on hospital-grade morphine.
Hunter and Nixon head off to Romania on a mission to find a missing woman and unravel a sex-trafficking racket.
Hunter and Nixon are embroiled in danger at every turn and suspect that their Romanian colleagues are in the pay of Nastase's people-trafficking outfit.
Yvonne gets into hot water helping a homeless man, Roger hits rock bottom, and a youngster is arrested for involvement in a protection racket.
Max Little is pushed to the limit by his ex-wife's involvement with big-time gangster Barry Green, and Leela bonds with a busker who is found beaten in the park.
An abduction case leads to a hostage situation when the suspect makes a getaway on a bus - and pulls a gun on Yvonne. Terry has wonderful news from his ex-wife.
Mickey wakes up in a strange bed and ends up being grilled at Mill Street station on rape charges. Personal issues continue to poison Will's working relationship with Matt.
Honey warns Emma not to rush blindly into marriage. A beaten prostitute turns out to be a drugs mule working for Paul Haskew.
Mickey investigates the disappearance of another sex worker, and Zain arranges to meet the supplier behind Kristen Shaw's drugs operation. Phil apologises to Sam.
Yvonne and Honey question a young tearaway about a break-in at a doctor's surgery. Emma chooses the wrong moment to tell Matt about her night with Will.
Will accuses Matt of having him beaten up, and ends up being arrested by Tony when he takes matters into his own hands. Yvonne makes an impression on Heaton.
Dan takes a shine to his flirtatious 'girlfriend' during an undercover sting operation - and turns up late for his first serious boxing match.
Nikki Wright, a sergeant from the Barton Street station, finds herself caught up in an armed stand-off along with her new Sun Hill colleagues.
Mickey investigates the severe beating of a sex worker and ends up offering her a room for the night, despite Jack's advice to avoid emotional involvement.
Billy Aldridge goes missing after making unsubstantiated accusations against GP Andrew Wilder, and is later found badly beaten up.
Linda Robson and Nicola Stapleton guest star in a domestic incident that takes a sinister turn when a power cut throws the Sun Hill custody office into darkness.
Will gets involved in an incident outside a nightclub, leaving his job on the line - even though the incident leads to the Sun Hill team foiling a raid on a jeweller's shop.
Jack becomes impatient for a result in the undercover operation to trap drug dealer Jose Alvarez, and Zain panics when he's pressed to set up a sting.
With the Serious Organised Crime Agency on his back, Jack orders Zain to take a break and brings Kristen Shaw in for questioning. Dan is suspended for abusing steroids.
Stuart and Terry are surprised to discover an ex-colleague working undercover. Honey and Leela sort out a scuffle at a funeral.
Reg and Tony are called to assist a council bailiff trying to evict a pregnant woman from her flat, but end up arresting the official for violent conduct.
Diane encounters an old army colleague, which brings back painful memories from her service days. Honey invites Will home after an evening in the pub.
A missing teenager refuses to return to her strict Turkish father and takes matters into her own hands.
John Heaton tells Gina that Sun Hill faces the threat of closure and the team pull together to keep the station on the map.