Responding to an urgent call for assistance, Smithy arrives and has to deliver a baby in the street. Worried about the mother's condition, he investigates her background, and discovers a history of prostitution and drug abuse. When she vanishes from the hospital and abandons her newborn baby, Smithy has no choice but to inform her father, who subsequently reveals that he and his wife will be adopting the baby and bringing it up as their own. Smithy enlists the mother's help to catch her pimp, who is also dealing drugs in the process, by setting up an obbo to catch him in the act. However, the obbo goes badly wrong when the girl makes off with the drugs and tries selling them herself to local users.

Probationary PCs Ben Hayward and Roz Clarke arrive for their first day at Sun Hill, and are subjected to a series of wind-ups by the relief. Boyden tricks Clarke into thinking that he has hit a pensioner in the surveillance van, while Stamp and Quinnan subject Hayward to the ride of his life in the area car. Hayward manages to stop a curb-crawler who evades capture, but his arrest is thwarted by Hollis. Meanwhile, Hagen and Rickman spin Clarke a story about 'nipper' Cryer, the famous bum-pinching sergeant, and Klein gets Worrell to be pretend to a dead body in order to wind up Hayward. However, the joke backfires when an angry and upset Hayward is punched in the face by Stamp.

Hayward and Clarke try to redeem themselves after a disastrous first day, and decide to exact revenge on the wind-up merchants on the relief. Ackland is furious to learn that half of the relief are involved in the wind-ups, but is even more upset to discover Boyden played the worst trick of all. Meanwhile, after a curb-crawling class at the station, Hayward, Clarke and Page investigate when a tom is burgled and the ashes of her best friend are stolen. Hayward and Clarke believe not only have they discovered who is responsible, but they may have cracked the identity of her best friend's murderer as well, however they are brought back to earth by a tragic twist. Clarke exacts the ultimate revenge on Klein after she discovers he fancies her.

PC Roz Clarke is on attachment to CID, and puts up with the usual teasing from the detectives and her uniform colleagues. She cracks the case she is working on with DC Glaze though, when she realises that a series of break-ins are all one surname in the phone book. When Ch. Insp. Conway and DI Cullen attend a rugby match between the Met and the Army, Conway is abducted when a disgruntled soldier decides to take revenge on those responsible for the abuse he received while at a children's home.

DS McAllister is surprised to run into her former lover and informant Jamie Ross in a bar, when he returns to Sun Hill after the man who wanted him dead dies of a heart attack. Ross is in a new line of work: organising adventure holidays - but he still has plenty of inside knowledge, and when he and McAllister resume their relationship, he reveals the man responsible for a hit-and-run on a drug dealer and a schoolgirl. To McAllister's horror, she realises that Ross has used her, as he is deeply in debt to Brett Sadler who ordered the drug dealer killed. DI Cullen convinces Ross to help them catch Sadler, but Ross is shot and killed by a sniper.

A distraught PC Roz Clarke fails her probation exams, and goes AWOL instead of returning to the station. A gang of thieves on rollerblades are rampant in Sun Hill, and their mobility makes it very difficult for the police to catch them. PC Taviner arrests a girl, Jackie Burns, at a skate park, but she insists she was just watching the skaters. As the skate gang gets more violent, animosity between PC Worrell and Clarke also grows more fierce, and the two come to blows in the corridor. A tearful Clarke admits her debt problem to Taviner. Scrutinising CCTV footage reveals Jackie's involvment with the gang - she phones them when a potential victim withdraws money from an ATM. Clarke returns home to find the bad news that her telesales commission has fallen through and her flatmate Caitlin wants her out.

PC Roz Clarke unsuccessfully applies for a police loan. PC Des Taviner buys her a pushbike and suggests she sell her scooter, but Roz is far from impressed. PCs Carver and Rickman find a young boy, Gavin Billson, overdosed on drugs, and CID investigate some of the local dealers. When it turns out Gavin overdosed on diamorphine, and after several dead ends, suspiscion falls on Dr Stuart Bremnar, a doctor at St Hugh's, who is also the boyfriend of Roz Clarke's friend Ruth. A review of the hospital's CCTV footage reveals Ruth herself sneaking into a storeroom, and Roz is forced to arrest her best friend.

PC Jim Carver is angry at suggestions the blaze was an inside job. He goes to his MIT interview thinking there's nothing to declare, but when they ask precisely what he was 'discussing' with Sergeant June Ackland just prior to the blast, he falters. If only he'd listened to PC Reg Hollis's warnings about guilty 'micro expressions'. The death of his colleagues has affected PC Stamp deeply so when he discovers a young lad has been nicking flowers from the Sun Hill wreaths he concentrates on tracking him down. In doing so, he directly disobeys June's orders to head straight to a mugging victim who's been waiting on the street for an officer. With the memorial service the following day Superintendent Tom Chandler's thoughts are on how the spectacle will reflect on his station. He orders Des to carry the Met flag but Des's priority is certainly not on becoming the station hero to focus on. It's his first day back on the job and he's not ready to be high profile. Chandler reminds him what po

It's the day of the memorial service and Superintendent Chandler is determined to make a good impression and a moving speech. While Des carries the Met Standard down the aisle the real weight is on his mind. He's just been assigned a babysitting task he'd really rather not have and all eyes are on him today. Reg lends a sympathetic ear and proves his friendship. Meanwhile Harry Fullerton, the decorator employed to renovate Sun Hill before the explosion (and top of the Murder Investigation Team's most wanted list), makes an unwelcome appearance. PC Tony Stamp can't believe the cheek of him and starts to cause a scene. Luckily the old guard is on hand with a characteristically level head. New CID member DC Eva Sharpe turns up for her first day on the job. After practically ploughing into DC Mickey Webb's car she's told to take over his case while he attends the service. While Mickey would rather not listen to the superintendent's eulogy he relents and Eva goes to keep an eye on local a d

Tait, after abducting his own daughter, Emily, decides to return to Australia, but realises that he is making the wrong decision and decides to return to Sun Hill. Best, suspicious that Mark Davies will refuse to name his attacker, decides to keep a close eye on Tait. When Mark Davies is discharged from hospital, he is involved in a hit-and-run, and later dies in hospital of his injuries, but Best discovers a link to a violent loan shark. Webb investigates when a man is found injured in a woman's home in mysterious circumstances. Meadows does all he can to prevent Rachel Heath from being charged with GBH, but when the victim presses charges, he finds that the matter is out of his hands.

PC Polly Page's horrible cousin Michelle turns up at Sun Hill, to report she is being stalked. Despite Michelle's obstructiveness, Polly manages to convince PC Cathy Bradford to get some information out of her so they can find the suspect. DCI Jack Meadows does all he can to prevent Rachel Heath from being charged with GBH, and when the victim presses charges, the matter is out of his hands. Sgt. June Ackland feels her age when she falls behind while chasing a bag snatcher. When an elderly lady is struck by a car and later dies in hospital, Ackland realises the dead woman could be the mother of DC Mickey Webb. DS Phil Hunter convinces DC Juliet Becker to tell his wife she was the cop having an affair with Heather Rayner, not him. As PCs Page and Bradford uncover details of Michelle's love life, Bradford's indiscrete line of questioning results in a complaint made against her and a tongue lashing from DS Ramani De Costa - but Bradford turns the tables once again by summoning crocodile t

A siege is underway… the gunman who took PC Gary Best's dad is now holed up in a building, and when Inspector Gina Gold finds out two elderly residents, one a diabetic in urgent need of medication, are trapped she has to decide whether to let SO19 take him by surprise. When Smithy volunteers himself as a hostage in return for the elderly couple to be released, his actions are totally against protocol, much to Inspector Gold's dismay. Smithy desperately attempts to talk the gunman down but he's dealing with a deranged man capable of anything. Will Gina Gold put her officer's life at risk by allowing SO19 to storm the building and will Gary Best ever have the chance to make amends with his father?

It's the last day of PC Polly's trial and she takes the stand to try and convince the jury of her innocence. But will she convince the packed courtroom that she did the right thing? And how will Polly's confession that she was set up by Cathy go down with her Sun Hill colleagues, especially wh

McAllister and Hunter investigate a serious assault on a prostitute, while Okaro is forced to deal with National Party councillor Nicola Marsh, who is trying to raise racial tensions by highlighting an increase in black-on-white crime. Best recovers in hospital after throwing Jules Ellis to his death from the station roof, and falling off himself. McAllister is saddened to discover that Becker died the night before, and Sun Hill deal with the fallout due to the death of the suspect, who swallowed his tongue in custody. Murphy admits to Okaro that Taviner was responsible for the Sun Hill firebombing when forensics discover that he wasn't killed in the Area Car warehouse explosion. Page is found guilty and sentenced to life in prison. Kent gets close to Ackland.

DCI Jack Meadow's former lover and ex-prostitute Rachel Heath (Lysette Anthony) is due in court to stand trial for assault. With the news that she's pregnant with his child, she tells Jack she intends to tell the court about their affair and go for a mistrial. With his police career on the line, Jack suddenly makes a surprise proposal but will former Sun Hill officer Mickey Webb be able to convince Jack he's doing the wrong thing? The pressure's mounting for DI Neil Manson when DC Eva Sharpe implies she knows about his father in law using rent boys. Neil learns of Jack's affair with Rachel which gives him the bargaining tool to get Eva off his back. Is this the end of Eva's time at Sun Hill? Elsewhere, DS Debbie McAllister investigates an attack on two boys but was the attack a racist or homophobic assault?

Gary uses his own experience to convince one of the victims to make a tough decision.

PC Andrea Dunbar arrives in the force and her keenness seems to good to be true, but little do the relief know that they have an undercover reporter among them. When Eva discovers that Debbie told Neil about Jacks affair she is furious and they fight. Tensions run high between DCI Jack Meadows and DI Neil Manson because Neil wants Eva out, no matter what and just as he is announcing her departure, Jack comes in with an offer for Eva to join MIT. Polly returns to Sun Hill as the new CAD operator but after she is snubbed by Neil during her shift she feels vulnerable and things get worse when she returns home to find the word 'murderer' painted across her flat window.