It's Halloween, and paramedics Josh, Comfort, Woody and Luke are giving a demonstration at Farmead, a failing school.
Young teacher Nick Bond oversees a boisterous class full of kids - excited about an up and coming Halloween party. It's a reward from valiant head teacher Carl for their improving behaviour.
Carl pulls Nick aside to inform him that he has to leave: he was going to give him until the end of term, but now he wants him to go by the end of the week. When Comfort finds Nick and a pretty pupil, Emma, looking intimate in a classroom, we realise why.
As the party begins, schoolboy Adrian persuades Emma to bob for apples - but someone has put acid in the water and she and her best friend Shania are badly burned. Emma calls out for Nick, and her unstable boyfriend Kris realises that the rumours about her and the teacher are true.
As the paramedics battle to save Shania's life, Josh's patience with these unruly kids snaps and he lashes out at a boy who has stumbled into him. Woody is not happy about the incident.
Ambulances arrive and take Emma and Shania to hospital. As the paramedics are preparing to drive their demo ambulance back to base, an injured Nick runs up to them, chased by Kris and his friends. The boys scatter as Carl calls the police, and Comfort and Luke pull Nick away from his attackers and into their ambulance.
But as they reach the school gates, Kris and his mates hijack the ambulance, throwing Luke out of it and screeching off, with Comfort and Nick still trapped inside.
Meanwhile back at Holby, the staff in the ED deal with a man, Connor, who has swallowed a sword. He has come in with a woman, Charlotte, who Abs discovers is his support worker. Abs is not sympathetic when she claims he had been trying to impress her and that she seems more concerned about losing her job.
Luke runs to tell Josh that the ambulance has been hijacked, sending Josh in pursuit on his bike. He eventually manages to overtake it and drives slowly, hoping to bring it to a halt.
Inside, Comfort has climbed into the back and is trying to protect Nick from further beatings by Kris and Paul. She is beaten in the process. Avoiding Josh at the last minute, the driver hits a car with the ambulance and in the ensuing chaos, all 3 boys run off.
Luke and Woody arrive and treat the victims in the car, an African couple, Edgar and Moji. Josh finds that Comfort only has a superficial head wound, but Nick is slipping in and out of consciousness. It is revealed that the car driver, Edgar is on the transplant list for a new heart. He has to wait for the fire brigade to cut him free of the car and nearly dies, but the paramedics save his life.
In the ED, Comfort's head is seen to and she rests in a cubicle. Moji finds out she is pregnant, but is determined that no one should tell Edgar while he is so ill. Nick starts to deteriorate and the staff struggle to stabilise him so he can be sent to theatre.
Carl, at the hospital to check on Shania, Emma and Nick, sees Adrian. He's behaving strangely and Carl guesses that he put the acid in the water which burned Emma and Shania, but Adrian won't tell him why. To get away from Carl, and panicked at the harm he has caused, Adrian takes out the acid he used and runs with it into Resus. He rushes up to Nick. Carl, pursuing, presumes he means harm and disarms him, but not without burning Adrian in the process.
Tess, returning to Comfort, finds that she is no longer in her cubicle and after a frantic search finds her collapsed unconscious.
Luke tells Josh that the paramedics will support him following the incident involving slapping a schoolboy.
Mary Stevens comes to the ED, with a man, Perry, who she has been on a few dates with, claiming to have abdomen pains When she is seen by Tess, she admits she is not in pain but is concerned about Perry, who has been behaving wierdly. When Tess confronts Perry, he informs her he has Parkinson's but hasn't told her. When he does, Mary is shocked and at first doesn't want to get involved. She then realises she doesn't know much about the disease and decides to give things a go with Perry anyway.
Comfort is taken to theatre, where Ric and Diane battle to save her life. They discover she has been stabbed when they find a small pierce through her skin.
Edgar, who was involved in the accident, is also taken upstairs. Connie takes over his case from Loftwood and discovers he is a prominent political figure back home. Edgar urges Connie to perform a high-risk operation on him, however Loftwood disagrees. However, Connie goes behind his back and goes ahead with the operation.
Emma reveals to Kris that it was Adrian who put acid in the water that burnt her face. Kris confronts Adrian, who is in ITU visiting Nick - it is discovered that Adrian had a crush on Nick, which is why he seeked revenge on Emma. Diane and Carl find them but Kris threatens them to back off or he'll hurt Adrian, the same way he hurt Comfort.
Chrissie gets her tests results back and they are all-clear. She hugs Owen and they nearly kiss, but she backs off and asks Owen to make a choice between her and Diane once and for all.
Edgar's operation is a success, but Loftwood is angry that Connie misled him into thinking she had 100% success rate in the procedure.
Edgar has been asked to return home and try and become political leader to help ease the suffering happening in his country. Moji tells him she is pregnant and that she is reluctant to go home. At first he decides to stay, but changes his mind when his friend tells him that his family died out there. He realises he must go back to help - Moji agrees to go with him.
Kris discovers that Carl knew about Emma's affair with Nick. He attacks Carl in the hospital toilets and runs off. Carl is taken to theatre, but dies of his injuries. Josh gives chase to Kris onto the hospital roof, where he threatens to jump. Josh persuades him to face up his responsibilites.
Matt asks Diane to be his mentor. Despite his recent behaviour, she happily agrees.
At the end of shift, Loftwood tells Connie that he is resigning. He tells her he admires her confidence and reiterates that his position will become vacant.
