Hearing that conman Charlie Dickens is 'going straight' and found a 'respectable' job, the cynical and experienced Gamble is sceptical of Charlie's claims. Vicky, however, is prepared to give him the benefit of the doubt - an unwise move.
Building tycoon Jim Harland's firm can only survive if he forms a partnership with a Dutch firm - a building company Gamble suspects of fraudulent activities. An inspection of Hardland's books is for, which, when checked reveals some surprising discrepancies.
A shock awaits Detective Gamble when he is called into his superior's office. Laughton, a tax investigator asks the detective a lot of disturbing questions - questions relating to the left-wing activities of Gamble's wife, Helen.
Gamble is asked to investigate the activities of a retired spinster, a woman responsible for administering a charity fund for the sick and needy - to which only payment has been granted in three years.
After receiving a complaint from a man whose wife died after being admitted to a clinic specialising in nervous diseases, Gamble investigates the establishment and discovers a ruthless doctor exploiting the sick for his own gain.
Roger Simms' youthful zest and flair for management has been shot in the arm for Burton Investments, but he dosen't get along with older and more experienced Arthur Mills, the man he replaced. Is that the reason behind Mills' accusations of discrepancies in the firm's books?
The Cosy Lamb Blanket Factory is losing money fast - partly due to its chairman, 80 year old Lady Flanders, but mostly due to petty pilfering. But does £40,000 come under that heading? Gamble thinks not - and investigates the firm.
The Fraud Squard team investigates a currency leak by keeping tabs on wealthy Harry Killett, whom they suspect of making his fortune by smuggling money out of the country. So when he deposits a large suitcase with an Investment Company, Gamble swoops - but the criminals are one jump ahead of him.
Winifred Holland, a wealthy spinster, lives with her mother and works for Captain Garland, a writer and explorer wishing to mount an expedition to search for Spanish treasure. Winifred is prepared to finance the treasure hunt - until Gamble points out that the real Captain Garland died five years earlier.
Fraud, extortion, vice - The Dysart Brothers are in for a percentage of everything. Outwardly respectable, their legitimate business is a front for criminal activities. Gamble is intent on tearing down their empire - by whatever means it takes.