Widowed psychiatrist Roger Corder runs his Harley Street practice with young assistant Jimmy and devoted secretary Nancy, as well as bringing up his precocious young daughter. When the managing director of a large business dies suddenly, there are two likely candidates, Phillips and Hunter, as his replacements. Dr. Corder is called in to assess which is the more suitable.
Because her husband, company director Henry, stays out until all hours and sometimes never returns until the next morning Julia Gray is convinced that he is cheating on her and attempts suicide. She is treated by Dr. Corder, who discovers that Henry may not have a mistress but he is certainly not as staid as he first appears.
Career soldier Sergeant-Major Bennett is being court-martialled and Dr. Corder has to write an assessment report on this seemingly cocksure man. However events seem to suggest that it is Bennett's commanding officer, Lieutenant Gray, who is the paranoid one and in the course of his investigation Corder exposes an enemy agent.
Given that she leads a comfortable life-style, lacking for nothing, Lady Shaw is one of the last people one would expect to be caught shop-lifting. However, when reports are called for and she gets to meet Dr. Corder it becomes evident that to some extent her uncharacteristic behaviour is a means of rebelling against her controlling husband, a severe High Court judge.
The two-edged sword is a reference to hypnotism and the fact that it can produce good or bad effects. In the case of Fay Bridges who, years earlier was hypnotised by a quack doctor, it has had a lasting unfortunate effect in her relationship with her husband. Dr. Corder, however, is able to use it to the good in the case of Doreen Stokes in helping her come to terms with the baby she has rejected.
Wealthy Geoffrey Petlen is married to the much younger Eleanor, on whom he dotes. One day she takes a shot-gun and blasts the swans on his lake. She confesses to being prone to unhealthy compulsions, as a result of which Geoffrey refers her to Dr Corder. What he does not realise is that she has met Corder before and has her own, unhealthy agenda for seeing him again.
Dr. Corder is called in to assess Bert Morgan, a young burglar. Not only does he feel compelled to break in to houses with gable but, once inside, he is obsessed with winding up the clocks in the room. Corder, going against the police view that Bert is mad, discovers the key to his odd behaviour is a wartime incident of twenty years earlier.
Jan and Rita Zapotski are a young couple who are still living with both of their sets of parents, a situation which is taking its toll on Jan, who feels frustrated and emasculated as a result. He starts smashing windows to draw attention to his discontent. It is down to Dr. Corder to sort him out, to find out his underlying motives and point him to a happy future in which he can be a master in his own house.
Elderly headmistress Dorothy Wyley comes to see Dr. Corder after she has attempted suicide and he unravels an unhappy chain of events. For one thing she has lied about her age in order to keep the job she loves and is afraid she will be asked to leave but more important is the unrequited love she felt for a pupil many years earlier.
Liz Kross descends the staircases at Charing Cross tube station, shedding her clothes as she goes and ending up nude on the platform where a bystander saves her from stepping in front of a train. She is arrested and referred to Dr Corder who discovers that she is working as a waitress and a stripper to finance an operation for her father, a fact which he resents and has caused her to subconsciously rebel.
When she was younger Jean Forrest was a big name actress but now she lives in fear of ageing and attempts suicide - as a result of which she is brought to see Dr. Corder for his assessment. Jean is hoping to make a stage comeback in the very near future but her ability to do so depends on the persuasion of Dr.Corder that she still has star quality.
The wealthy financier Sir William Bridley has recently died but both his will, made twenty years earlier, and his sanity are being challenged and Dr. Corder is called in as arbitrator. Either Sir William was a monster or a giant among pygmies and the doctor must decide who is telling the truth, the amiable widow or her fearsome sister-in-law Agnes.
Christine Box, a normally placid, unmarried teacher at a tough secondary modern school, uncharacteristically lashes out at a pupil and is charged with assault. Though found guilty she is allowed back at the school because of her previous good record and once again has another lapse. Dr. Corder delves into her family and social background to understand how she has suddenly taken on a new violent streak.
Formula one racing driver Jimbo Harris is obsessed with breaking the lap record to the extent that whilst he has a clear lead in his race he accelerates and crashes, injuring himself. Dr. Corder has to discover the reason for this obsession, hopefully in time for Jimbo to drive in the Monaco Grand Prix and draws a connection with Jimbo's time serving in the Korean war. However, against the doctor's advice Jimbo breaks off treatment to claim that all-time record at Monaco.
Patrick Grant is an over-worked designer whose wife Catherine insists on living beyond their means. He meets Joy, who owns kennels, and they fall in love. But when Joy gets pregnant by Patrick and asks him to leave Catherine and marry her, he caves in under the pressure, requiring Dr. Corder to sort him out.