Dixie (Jane Hazlegrove) and Jeff (Matt Bardock) face new competition in the form of new paramedics Omar Nasri (Dhaffer L'Abidine) and Tamzin Bayle (Gemma Atkinson) and just when they think their day couldn't get any worse, they are called to a farmhouse and are met by a drugs baron and a pack of wild dogs. Jordan (Michael French) begins to panic that the symptoms of his previous tumour are returning.

First appearance: Omar Nasri (Dhaffer L'Abidine) and Tamzin Bayle (Gemma Atkinson)

Charlie (Derek Thompson) welcomes two new nurses Lloyd Asike (Michael Obiora) and Scarlett Conway (Madeleine Mantock) and whilst Lloyd gets off to a good start, Scarlett is more interested in the hospital's anaesthetist George Murphy rather than the patients. A teaching assistant (Lee Mead) gets beaten up in a fight between a senior colleague and a problematic student.

First appearance: Lloyd Asike (Michael Obiora) and Scarlett Conway (Madeleine Mantock)

Several patients are brought into the department suffering from strange but similar symptoms and their condition continues to deteriorate, Dylan (William Beck) faces a race against time to find the common link. Lloyd and Scarlett struggle with the demands of their duties. Linda (Christine Tremarco) is attacked by two drug addicts.

Lloyd's refusal to break his moral code and lie to a patient leads to him clashing with Jay (Ben Turner) and then confiding in Tess (Suzanne Packer) about his grievances. A patient mistakenly believes she is being stalked. Zoe (Sunetra Sarker) discovers that Dylan helps out the paramedics at accidents scenes on a voluntary basis.

A drug addict relapses leading to the future of Charlie's clinic being put on the line when a drug dealer turns up at the department. Jordan's "complacency" drive ends with Zoe getting an unexpected promotion. The re-appearance of an estranged brother at a funeral ends in a brawl and a shocking revelation.

As a drug addict recovers from a beating, Linda blames Jordan for closing the drugs clinic which would have kept her safe and has to choice between breaking the law and saving the drug addict. Jeff and Omar clash over Omar's believe that targets should be put before the patient.

Sam Nicholls (Charlotte Salt) an army medic joins the team on a secondment and begins by joining the paramedics for the day and has to act quickly when the ambulance is forced off the road. Noel (Tony Marshall) wants to increase security around the hospital but a confrontation with a grieving mother soon changes his mind.

First appearance: Sam Nicholls (Charlotte Salt)

Linda sticks her neck out to help a heroin addict and her baby daughter escape her violent pimp but she ends up risking Tess' wrath in the process. Zoe is highly amused when she discovers that Dylan and Sam have a history, especially when she mocks his attempts to be the Sherlock Holmes of the medical world.

Sam helps a teenage mother come to terms with the fact that she isn't a bad mother. Ruth helps an elderly couple come to terms with a terminal illness. Ruth confides in Jordan that she is feeling weepy and distracted but she then makes a surprising discovery.

Ruth and Jay's relationship seems stronger than ever until Ruth suffers a major wobble. Linda's enemy returns and plans to kidnap his baby daughter. As Jordan tries to address some fire hazards, a socket outlet overloads for the last time and soon the fire alarms begin sounding.

Lenny and the fire officer alert everyone to a fire in the basement of the building and Jordan orders an evacuation. Jay confronts Ruth over why she dumped him but soon they have bigger problems when the fire traps them in an office and as an explosion leaves Zoe and Dylan trapped in resus, will any of them make it out of the building alive?

Final appearance: Jay Faldren (Ben Turner) & Ruth Winters (Georgia Taylor)

The ED reopens to minor cases following the fire but the team are forced to change their plans when a traffic incident on the dual carriageway brings casualties flooding into Holby. The situation worsens when a related traffic incident causes a gas pipe to explode and poisonous gas engulfs the town. Despite the efforts of new paediatric doctor Tom, (Oliver Coleman) the ED is at full stretch. Will the ED team cope with one of their most challenging days yet?

Note: First episode filmed from Cardiff, and shown in HD.

Following his heroics during the explosion the previous day, Tom formally joins the team at the ED and his first case soon turns into a mystery when a family caught up in the explosion return to the ED with mysterious injuries. Big Mac (Charles Dale) turns into an unlikely hero when a young son from the family is then kidnapped. Dylan accuses Sam of meddling with a patient's home life but will it turn out to be for the better? Jordan's feathers are ruffled by a young attractive DCI.

When a woman is rushed into the hospital with broken ribs and no memory of what took place, Lloyd insists that they investigate but has he unwittingly sent her back into the dangerous situation she was trying to escape from in the first place? Linda is horrified when her sister Denise and her children turn up at the ED and even more shocked when she finds out her sister is still a drug addict.

First appearance: Britney Andrews (Devon Beigan) & Joe Andrews (Taylor Parry)

In the second episode of this two-parter, Linda's niece Britney faces serious danger from an internet predator, while on Lenny's last day in Holby, his medical skills are put to the test. Britney has arranged to meet someone she met chatting online, but the man is not 19 years old as he claimed to be. When the man takes Britney back to his flat, she soon finds herself in an extremely threatening situation. Can Lenny and Linda track her down in time?. Meanwhile, the Chilcot family are back in the ED after a fight breaks out in a nightclub and eldest son Matthew collapses. Dylan diagnoses that Matthew is a sickle cell sufferer and that he will urgently need a bone marrow transplant. What more family secrets will be revealed as they search for a perfect tissue match?. Elsewhere, Scarlett and Lloyd fall out over her treatment of his family, and the team bids farewell to a prickly but popular colleague.

Sam has high hopes of returning to Afghanistan, but when she falters during a training exercise, she is forced to question whether she will ever be ready to face a war zone again. On her way home she comes across Captain Morrison, a former army colleague, who is slumped in a crashed vehicle. Suspecting that he has had an epileptic fit, she is torn over whether she should tell the army the truth of her suspicions, which could end his military career. Meanwhile, new nurse Fletch (played by Alex Walkinshaw) joins the ED team. He makes a favourable impression with everyone - except for Lloyd. The pair are forced to work together to help Amy, whose initial joy at discovering she is pregnant turns to horror when the true diagnosis is made.

First appearance: Adrian "Fletch" Fletcher (Alex Walkinshaw)

In the Concluding episode to both this tense two-parter and the series, A vigil for Wesley Royce blows up into a full-scale riot, and Scarlett is swept along with the rioters. In a face-off with the police she finds herself on the wrong side of the law. Unsure of which way to turn, she is pressured into helping a severely injured rioter. Picking up the pieces, Lloyd comes to the horrible realization that he really doesn’t know his girlfriend. Dixie and Jeff are dispatched to pick up the gravely injured Yvonne, after she was stabbed by a panicked shopkeeper, who mistook her for a rioter. She appears to have sustained a really bad stab wound and critical head and spinal injury after she fell down the stairs when she was stabbed. They realize she needs immediate critical care and request a doctor. Jordan goes, but can he keep his emotions in check and do the job? In the ambulance on the way to ED, Yvonne stops breathing. Jordan is forced to perform a dangerous life saving operation in the ambulance, as the riots block their way.

Final appearance: Scarlett Conway (Madeleine Mantock)