It's Mac's last day and Sue and Caroline are struggling to cope with the thought of losing him. While Sue offers to kill in order to keep Mac in the hospital, Caroline spends most of the day trying to find fault with Sheffield in order to deter him from leaving. Meanwhile Martin finds himself in a tricky situation when he reads a personal letter of Guy's and discovers that not only is Guy adopted, but that his real mother was called Joanna Peerson – the surname of whom also happened to be the maiden name of Joanna Clore. Unaware that his mother and work colleague are one of the same, Guy has no qualms in taking up one of Mac's bets to prove his prowess with the ladies by bedding an older woman of Mac's choice – Joanna. When Martin later discovers his half-brother's intentions he rushes over to stop it – which ends in a botox stabbing, staff on the run from the police in an ambulance and a major cliff-hanger – literally.

Caroline engaged to Guy, Mac getting closer to death, Statham and Joanna on the run, Karen acting strange and the admin girls letting their hair down a bit lower than normal.

Joanna is turning 42, but her day brightens up when she mistakenly thinks she has received a locket as a birthday gift from Lyndon, when it is in fact from the ever doting Dr. Alan Statham (filled with his own "love juice"). Meanwhile Guy is compiling a fanciability league table of all the female staff, the results of which don't go over too well with Dr. Caroline Todd who retaliates with her own ungenerous male staff summary (but Guy is still happy to be the aggregate total winner). Elsewhere Boyce and Martin use the CT scanner to weed out the money prizes in packets of crisps, the former of whom also spends as much time as he can taunting Dr. Statham about his gay tendencies. And Caroline tries to adapt to living with Angela's active sex life and harp playing.

Hormones are abound in the hospital with Mac the centre of both Caroline and Sue's affections, Boyce and Kim having fun together and Karen writing a love poem about Martin who in turn is desperate to impress Caroline. And of course there is Joanna (sporting a new bleached hairdo) who is still after Lyndon much to Statham's annoyance, and so after listening to Boyce's advice on women, decides to act mysterious by playing 'kidnapper' and having his way with Joanna in the woods. Meanwhile Caroline and Angela decide to throw a party and the hospital staff are invited – including an apprehensive Martin who can't decide on what to wear. After turning down Sue's selection of clothes from the ‘dead people box', the Staff Liaison Officer takes him shopping for the perfect outfit with interesting results.

The hospital is hosting a charity Grand Slave Auction with Statham, Caroline, Guy and Lyndon all up for bid and while there is high competition for some, others aren't so lucky. Meanwhile Caroline falls on Sue's bad (and murderous) side when she admits to having feelings for Mac, but Mac surprises them all by revealing his new girlfriend Lady Emily and by the announcement that he his leaving the hospital after being offered a consultancy position in Sheffield. Martin decides that the way to win Caroline's heart is by being a bastard, Joanna finally finds out where she stands with Lyndon and Harriet is called into the school to talk about her troublesome son.

Mac adjusts to his new rôle as a father while Caroline tries to make him jealous with Guy. Statham is rather pleased with himself for winning his radiologist's community weekly caption competition which does not please Joanna. She employs her vertically-challenged cousin to scare him but a trip to the incinerator is soon required. Martin pesters Joanna for knowledge of his dad and hires a detective to find him.

Sue does some detecting; Martin comes into some money; Statham and Joanna try to keep the incident with the stuffed heron secret; Caroline has to be cruel to be kind.

Demented dwarf killers Joanna and Dr Statham are amazed that they seem to have got away with their hideous crime so consider themselves above the law. Caroline gets no fewer than three proposals. Sue gives birth to an infant with a mane just as impressive as Mac's. Mac gets some bad news while Martin (and we the viewer) ends up with a strange sense of déjà vu in the season's cliff-hanger ending.

Hungover and worse for wear, Caroline is feeling the effects of the party the night before, which she still can't completely remember. When her kissing exploits come back to her, she is forced to trawl the hospital to apologise to everyone she kissed and insist it meant nothing – even to Mac, who of course it meant everything with. Meanwhile both Harriet and Joanna think that they are pregnant and are soon taking trips to the path lab. While Statham is ecstatic at the prospect of becoming a father, Joanna is far from thrilled with the positive result – until it turns out the results were mixed up with Harriet – leaving Harriet the depressed one and ending with Joanna breaking up with Statham. Elsewhere in the hospital Mac secretly has an interview for a better job, while Martin continues his quest to further his own career by taking his doctor's exam yet again.

Statham still isn't completely over Joanna and spends all his day trying to win her back by pretending to hang himself, singing ‘All By Myself' to her via a megaphone and by challenging Lyndon to a tug-of-war in the cafeteria for the hand of Joanna. However when he meets the hospital's chaplain Cordelia he soon finds another object for his affection. Meanwhile Caroline is feeling broody but is having conflicting thoughts about who should be the prospective daddy. Still infatuated with Mac, she also finds herself drawn to Guy and his ‘layers' - most of which he invents in order to manipulate her into a date out in the countryside. Martin gets his exam results (which are held hostage by Sue for most of the day) but discovers he has failed yet again – however not until Guy evilly convinces him he has passed. And a cardboard cut-out of Jesus keeps popping up around the hospital.

A documentary crew visits the hospital, exciting the creative juices in Alan and the bitter rivalry between Sue and Joanna. Meanwhile, a tape of Guy being "intimate" with his mother is now in the possession of Sue who plays merry havoc with his and Joanna's life. And is this the end for Angela as she falls for the charms of the director who's off to Toronto next week?

Guy's got problems, he's looking for a place to stay while fulfilling his community service. Martin is in need of some cash so acts as a life model at an art class attended by the soon-to-be-gobsmacked Sue. Statham is distraught at his parking space while Joanna might need glasses. Mac and Caroline's relationship is hotting up but could all that change as his ex-girlfriend joins the staff?

Dr. Statham enters politics but requires a voice coach and the use of a car with two loudhailers! Martin inadvertently becomes a pimp. Mac and Caroline get a little closer but Holly sticks her oar in with a little ginger surprise for Mac. Harriet and Lyndon manage to have a date despite Joanna's best attempts to sidetrack her with work. Guy is not exactly the best flatmate but is he there at the right time for Caroline?

Statham, when not drawing breasts upon his x-rays, is trying to make Joanna jealous with increasingly desperate pretend sexual exploits. Mac is back at work and, with no help from Guy, is causing Caroline grief as he can't remember the twenty minutes that they were an item. Meanwhile, Karen and Martin have moved on to the next level and she's wearing him out.

Worried about her age Joanna is also concerned about the dreariness of her relationship with Statham, who in turn tries to spice up their relationship through spontaneity (with the help of playing his recorder to get himself sexually aroused). However he soon becomes concerned that I.T. wiz and women-pleaser Lyndon Jones is trying to steal Joanna away from him. Meanwhile Mac discovers that despite protesting she never wanted children, his ex-girlfriend Holly is expecting with her new partner. A delighted Guy soon uses this as ammunition in his game of one-upmanship with Mac, but ends up being traumatized himself when memories of his boarding school days come back to haunt him. And Caroline juggles her nicotine urges with searching for a new roommate, but is less than thrilled with the candidate being Angela.

After being locked out of her new house all night, Dr. Caroline Todd is forced to turn up to her new job at the local hospital tired and smelling like a mini-cab after using car freshener as a replacement for deodorant. She soon meets the strange staff, but anaesthetist Dr. Guy Secretan is very welcoming and offers her his spare room for the night while he works a night shift. However after a blocked toilet incident, she soon realises Guy's true motives after he turns up home early and she discovers there isn't actually a spare room. Meanwhile Dr. Alan Statham is having troubles of his own after someone defaced his badge by blacking out the letters O,N,S,L,T and A from his Consultant name badge, and his secret lover, Head of Human Resources Joanne Clore, tells him he isn't particularly well endowed – prompting him to check a corpse for comparisons sake.

While Joanna is extra careful to make sure that her and Statham aren't seen arriving together, Caroline isn't quite so lucky when she is spotted turning up with Guy after having spent that night at his place. Despite Caroline assuring everyone nothing happened between them, Guy is happier to play up to the rumours spreading around the hospital until Caroline forces him to admit the truth by digging up some dirt to blackmail him with. Meanwhile Martin is on the hunt for his missing soya yoghurt after it has been moved by the cleaners, Mac discovers that his old girlfriend is getting married, Statham spends the day enjoying how his white coat swirls around him, Sue tries to get her hands on Mac's hair and Harriet loses one of her many children.

It's eight weeks since Guy stole the ambulance and drove to a literal cliffhanger ending with Mac and Martin in tow. Mac is now in a coma and is receiving a constant stream of admiring visitors while Guy is not coping too well with the fact that he's slept with his mother. She's not having a great time of it either with her office staff's constant ribbing. However, Martin is happy to have a new brother and he's now gone as far as kissing Karen's tongue!