Young Norman Binns is admitted to Dr Thorpe's ward and is tricked by pessimistic Roy Figgis into swapping beds so that Figgis can have the bed with the window view. As a result, Thorpe and staff nurse Gupte confuse the two men's symptoms.
Norman has to have an appendectomy but Figgis' doom-laden description of operations and Thorpe's wariness do not give him confidence, so he hides in the toilet, having to be coaxed out.
Thorpe is telling Gupte that his dog Victor is unwell but Gupte misunderstands and thinks he's talking about his son. The patients also fall prey to the misunderstanding, for various reasons each believing that they are going to die.
Glover has been seeing a Greek girl and panics when her violent boyfriend comes looking for him so Figgis wraps his head in bandages, claiming that he is a burn victim, setting up a series of confusions.
Fed up with the quality of the hospital buffet, the patients go on strike but are soon defeated. However, server Clegg decides to go on strike himself, but has his foot run over whilst on picket outside the hospital.
Norman is reading a hospital romance, when he sees new nurse Sally, who is exactly like the fictional heroine. He wants to express his feelings but finds rivalry in Glover, Thorpe and Gupte, all keen to pursue.
When Glover is discharged, an unhappy Figgis, without someone to quarrel with, goes to the pub, pretending to be a doctor and diagnosing people with terrible illnesses, filling the ward.
Glover is thrilled when glamourous starlet Gloria Robins is admitted to a woman's ward and is before long romancing her with flowers. Characteristically, Figgis is cynical but even he falls under her spell – as do Norman and Thorpe.
Glover does not take kindly to eccentric new patient Joe Perkins – with his invisible dog – due to his lack of hygiene and use of Glover's drinking tumbler for his false teeth. However, when he discovers that Joe's tin box contains a fortune and the man is considering changing his will, Glover – and Norman – both fawn on him to get into his good books.
Norman has recently taken up smoking but long-term smokers Glover and Figgis are feeling the ill-effects of the habit and try, respectively, a pipe and yoga to help quit – but in vain.
When Figgis becomes obsessed with tabloid astrology, the others are sceptical — that is, until Norman's luck at cards takes an upturn. However, Figgis becomes so preoccupied with predictions, he becomes convinced that his death is imminent, forcing Thorpe to beat him at his own game to cure him.
Norman's overbearing, hypochondriac mother comes to visit and he's initially scared to tell her he is romancing Nurse Jenny. Norman's cowardice gives Glover the opportunity to try and make a move but Figgis puts him off with lies, enabling the young couple to eventually stand up to Mrs Binns.
When the vicar comes to discuss Norman and Jenny's impending nuptials, agnostic Figgis gets into a religious argument but ultimately fears for his soul as he has not been christened.
Feeling wistful that they're unable to attend the staff dance with its majority of females, the patients decide to have a party of their own, inviting Nurse Eileen. Needless to say Figgis and Glover – and Thorpe – vie with each other to impress her with their moves.
A TV crew arrive to shadow Thorpe for a day. He has primed Norman to give a glowing report but Norman keeps fluffing his lines, leaving Glover as only too keen to take over.
When new doctor Amy Glossop starts on the ward, Thorpe is initially hostile due to her gender, though both Glover and Norman have fallen in love with her.
Extreme right-wing MP Sir Julian Briggs is admitted to the ward, angering socialist Figgis, though Thorpe is anxious to get him on side as the hospital faces closure.
Believing that Glover is lonely, Figgis writes an anonymous letter in character as Glover to agony aunt Clare Butterfield, who is annoyed by the writer's arrogance. However, Glover has answered an ad and is expecting a visit from the free-thinking Leonora.
Norman witnesses an accident outside the hospital gates involving Thorpe and young speed freak Ronnie, though it is the doctor who would appear to be in the wrong when his breath sample proves positive. Figgis and Glover stage a mock trial to get Norman to divulge the truth.
Norman has been keeping a diary and Figgis and Glover are anxious to see what he's written about them. Upon stealing the diary, they find that most of the entries are fantasies in which Norman is the brave patient soothing everybody else's nerves, as well as inventing a romance between himself and the notoriously icy Nurse Bradley.
Figgis takes exception to the hospital radio run by Nurse Victoria and, when she accidentally leaves her recording equipment, spices things up by taping and broadcasting one of Thorpe's tirades.
On Christmas Eve, the ward gets a new patient, eight-year-old elected mute Danny, a known arsonist whose parents are abroad. Figgis dresses up as Father Christmas to steal presents for him from the Children's Ward but is rumbled and has to escape, getting the benefits of kisses from nurses who mistake him for the hospital's other Father Christmas.
Thorpe believes that Glover needs a blood transfusion and Figgis is the same blood group but Glover, being a snob, is not happy to be the recipient, especially when he hears that Figgis has received a transfusion himself from a West Indian.
Thorpe becomes an unlikely sex object when nymphomaniac patient Fiona demands they run off together and has written a complaint letter to the hospital board, whose chairman is her father, unless he agrees to her demand.
Having borrowed a book on psychiatry, Figgis takes it upon himself to analyse his fellow patients, alleging that Glover has a persecution complex and Norman is sexually repressed.
A most reluctant Norman is to marry the dull and plain Deirdre, rather than Jenny. Glover decides to flatter Deirdre in order that she might blossom but rather overdoes it so that she transforms into a glamorous, confident woman with no need for Norman.
Glover is charmed by new admission Harry Bridgewater - until it transpires that he is a prisoner who has come in for an operation with a guard in attendance. Having tried to pass himself off as a hardened criminal, Bridgewater has to admit he is merely a getaway driver but asks the patients to cover for him whilst he escapes – for a night – to be intimate with his wife. They agree and persuade Thorpe to assist them but will the convict really return?
An elderly drunk named Charlie arrives, claiming to be looking for his son, from whom he has long been estranged. The assumption is that his son is Norman, though it turns out to be Glover, who, after initial disgust, starts to warm to the old boy, especially when Charlie promises to lay off the sauce.
The patients are discharged on the same day – somewhat reluctantly given their lengths of stay – and decide to have a reunion the same evening in a restaurant. By chance, Thorpe is there with Hilary, who is emphatically not his wife, and when Thorpe goes to make a phone call, Glover, seeing her alone, moves in and succeeds in going home with her.
