The boys return for their second year, Michael's father having given him a stethoscope and a little blue book in which to write down cases, though it gets stolen. The students are dismayed to find that Professor Loftus will be teaching them for a second year running. He orders Michael to examine Miss Walker, a girl with a lump on her breast, who turns out to be ticklish despite Upton's efforts to warm his hands. After Miss Walker has gone Loftus orders Michael to strip so he can be examined by the others.
The students are let loose on a ward where each is assigned a patient whom they must assess with a report by mid-day. Michael ends up with Mr. Drobnic, a Slav with no English, who manages to elude Michael in his electric wheelchair. Michael thinks he's caught up with him only to find he's ended up with a pregnant woman whilst his patient is carried off in an ambulance.
The lads visit a Soho strip club where the star attraction is Rita, who comes on in a traffic warden uniform before peeling for her art. When she collapses she is taken to St. Swithins where she becomes a centre of attraction as a patient. Once cured she considers taking up nursing but isn't very good so she makes a compromise by using a nurse's uniform in her strip act.
Without a car to take the lads to a rugby match in Cambridge, Collier invests in a hearse, which he parks outside the mortuary. Two orderlies load a coffin onto it and the lads drive off unaware of their cargo. The police, alerted by the mortuary attendant, give chase and Collier drives the hearse to some woods where the coffin is revealed to contain a curious poacher. After the match the coffin is returned.
Waring volunteers to be hypnotized in a class by Dr. Towers but is actually faking it. Later Upton does successfully hypnotize him, getting him to mark at the mention of the word Dog. This annoys Towers, in whose class this happens. Waring dozes off and starts sleep-walking, ending up on the roof. The others get him down and take him to Towers, who gets him out of his trance but in the meantime Upton has hypnotized himself.
Upton and Waring have been chosen to observe Loftus on a two week residency in surgery but Upton is terrified and has a nightmare about an operation. When his friends reveal his phobia to the professor, a plan is hatched whereby Upton is made to assist Loftus in a crisis to perform an emergency operation on Waring. After Loftus has told him that as a young student he also had a morbid fear of operations, Upton sees that it was all a trick for his benefit but it has cured his phobia.
A Royal couple are to visit and unveil a plaque, commemorating the opening of a new ward. Anti-Monarchists Collier and Hooley, an Irish medic, steal the plaque and replace it with a toilet seat cover. Upton and Waring save the day by retrieving the plaque and replacing it but, as it is unveiled it is seen to be upside down - and then falls off the wall.
When Professor Loftus discharges elderly Mrs. Brown, claiming there is nothing wrong with her medically, Upton takes pity on her and visits to see if she is all right. In fact she is a very manipulative woman who, from time to time, pretends to be ill in order to prevent her daughter Margery from leaving home. Upton dates Margery but she is too much under her mother's thumb to leave her for a life of her own.
Upton is put forward to edit the medical student magazine 'Tonic'. Ingrid, the glamorous girl-friend of medic Dave Briddock, is the cover-girl and there is even a centrefold. It is a huge success - 4000 copies being printed and sold all over London, including in Parliament. Professor Loftus, however, is displeased and demands the withdrawal of every copy, which costs Upton and his friends. However Ingrid has been signed up to pose for 'Plaything' magazine as a result so she and Briddock will foot the bill.
Though no good at first aid Upton and Waring spend a fortnight in casualty. A shop-keeper who was injured in a robbery is brought in by a policeman. Later another man, with an injured ear, arrives and Upton perceives that this is the robber. He runs away but returns later, threatening Upton and Professor Loftus, who has also come in as a patient, with a knife. They are to stitch his ear but they stitch it to a pillow and he is eventually knocked out by the policeman using the enormous bandage that the students have wound around his arm.
Michael chats up Jenny at a party, unaware that she is dating Danny Hooley. The lads fall out and to make things worse they must work in the lab as a trio all week. Michael tries to swap shifts to ease matters but ends up kissing Jenny - leading to another fight. They take her out to dinner but fight again as nobody can agree on what to order. Eventually she gives them both up for another man.
A cameras crew is to make a television documentary at St. Swithins and Professor Loftus asks Michael and Dick Stuart-Clark to appear. The other medics are riled and try to sabotage the show, such as Danny Hooley pretending to be an elderly female patient. The crew also capture Loftus and Dick disagreeing over a diagnosis and some very rowdy behaviour in the student bar. It is ultimately revealed when everybody watches the show that its point was to highlight failings in the N.H.S. but Professor Loftus has had enough and wants it switched off.
It's time for the lads to take their qualifying exams and Michael is so anxious to stay awake for them he takes pep pills - which turn out to be sleeping pills. Thus he falls asleep on the bus on his way to the exam and misses his stop. He flags down a motor-cyclist, who gives him a lift to the hospital and has a heart attack in the car park. Michael saves his life but misses the exam. Professor Loftus is extremely angry until the motor-cyclist comes forward to explain what happened - and Michael qualifies with the others.