Three bullets, a dead man, and £50,000 in insurance. Troubles arise when Dr. Hardy discovers the Unknown Factor.

Penny Goodwin shoots her husband in cold blood and there appears to be no motive. Why she has killed him is far from clear. When Hardy starts an investigation, he uncovers a most ingenious plot which even Fleming will not believe.

Actual causes of death and accurate timing of the death can be essential to a defense in a trial. Dr. Hardy appears as the expert witness for the defense and finds himself opposed by his former professor.

Miss Daley has given up working because her old boss is leaving. She finds out that he is still with the firm and becomes very ill. She goes to see Jo Hardy and tells her that she's convinced she has heart trouble.

A girl is assaulted in a park and the only witness is her young daughter. The police are certain they know who did it, but the girl cannot identify the man in an identity parade.

Mr. Toller is a who has no time for the weak or the idle, without humour. Jo Hardy is treating him, he is arrogant and she patiently tries to diagnose what is causing his illness, which becomes more and more serious.

A woman is found dead by the side of a railway line. Hardy is brought in to help the police. The woman has been murdered, and as they investigate, the police and Hardy realise that they have a dangerous psychopath loose in their area.

An old man dies. When his housekeeper returns some unused tablets to the chemist, suspicion clouds the issue. Dr. Hardy is brought in to conduct various tests and he questions the principals in the case.

A man falls overboard from a ship near Hull and washed ashore dead. Injuries sustained in the water means he is unrecognizable. The most careful planning can go awry and only an expert can interpret the facts with which he is presented.

A safe is blown. The job has all the trademarks of a known criminal. Fleming pulls in two men in for the crime but forgets he needs concrete information to pin the crime on them both.

The death of small children is always tragic. The tragedy is increased by unspoken prejudices and the possibility that one of the parents may be to blame.

The Hardys are enjoying the peace of a summer evening. There is the noise of a shotgun. A man is brought to Dr. Jo's surgery with a non-fatal shotgun wound but John decides that this is a case for the police.

A drunken driver is responsible for the death of his brother-in-law and business partner and for the death of the driver of the second car involved in the accident. Hardy's concern for the facts leads to an exciting conclusion.

Murders take place and each crime is similar to the last. One person must have committed them; but who? Another attack. The victim survives but has amnesia and is the only person who can make an identification. A suspect is arrested.

Hardy is trying to piece together the burnt pieces of paper found in the suspect's room. Jo has been asked to try and break the surviving victim's amnesia by hypnosis. The suspect is questioned at length. The case builds up against him.

Martin Ingram, who has been arrested for assaulting Vivien, stands trial for his alleged crime. He is defended by a brilliant woman Q.C. The result of the trial remains in doubt until almost the last moment.

A smashed lock, a bloodstained jacket, a drifting boat and a takeover bid. Dr. Hardy with the aid of a few bright feathers and silk thread solves the mystery of a disappearing man.

When violent death strikes down a pretty farm girl, Dr Hardy and Inspector Fleming come up against a wall of stubborn reserve. Persistence at last brings Dr Hardy to a 'not inconsiderable suspicion' of the killer's identity. But proof.

Illegitimate babies present problems. Bringing one up in an atmosphere of disapproval can be harder than the alternative. To some, the decision is easy; a matter of practical common sense. To others it's life and death.

A man is found guilty of murdering his wife and sentenced to life imprisonment - could he be innocent? Unquestionably, the facts prove him guilty. Or do they?

Estate Duties - a curse to be avoided? When a businessman is found drowned it could mean ruin for his family.

That little Lucille died a violent death was certain; how she died was more obscure. Dr. Hardy's painstaking research and insistence on accuracy finally establishes the truth.

Protection: you can refuse to pay, you can go to the police for their protection - or you can stand the risk yourself.

A grocer, Harry Kirby, lies dead - poisoned, electrocuted, and gassed. If suicide can be established, surely this is gilding the lily. Why was a large sum of money found laid out neatly beside the body? And if it wasn't suicide.

An old man relies upon his daughter to look after him during convalescence but she has her own life to lead.