The book starts with Mr Finchley preparing to propose marriage to Mrs Crantell, the woman he had met in Cornwall in the previous book, but he is interrupted by the arrival of her brother and the opportunity is lost. The next day he is told to go to Paris to interview Mr Hammerton, a client of the law firm he works for, about a recent inheritance. During the Channel crossing he meets an eccentric entomologist called Laurence Hume. In Paris he befriends and is shown round Paris by Robert, an orphaned English boy being brought up by Pépé, a French barge-keeper, but basically running wild round Paris. On a boating lake they capsize a boat being rowed by Laurence Hume, who then persuades Mr Finchley to move from a hotel into his lodgings.
Mr Finchley eventually meets Mr Hammerton at the luxurious Marivaux Hotel, in which another guest is a boy millionaire called Alfonse Reims. Robert accompanies them when they go to dinner, and afterwards, when they visit a fairground, an apparent attempt is made to kidnap Robert.
The next day Mr Finchley and Robert are abducted and taken to a mysterious house near Versailles. There they encounter Jerome Giraud, a revolutionary who thinks he has kidnapped Alfonse Reims and has posted demands for huge sums to be paid to charities against his safe return. At first he refuses to believe that he has got the wrong child, but releases them in the end.
Back in Paris, it turns out that Pépé has abandoned Robert, leaving a letter saying he thinks Robert will be better off with his new English friends. Mr Hammerton volunteers to adopt Robert, but asks Mr Finchley to take care of him meanwhile. Mr Finchley and Robert go to London, where Robert gets into numerous scrapes. In the end it is Mr Finchley who adopts Robert. He completes his proposal of marriage to Mrs Crantell and is accepted.
One of the problems of the book for the modern reader is that many of Mr Finchley's actions, perfectly innocent by the standards of the time, would have Social Services being called out nowadays. Nobody seems to have read anything sinister into a 10-year-old boy spending time in a hotel room with an unrelated 46-year-old man. Nor are any eyebrows raised when Mr Hammerton, who scarcely knows Robert, impulsively offers to adopt him, meanwhile entrusting him to Mr Finchley for a few weeks.
This was the second book featuring Mr Finchley, the middle-aged clerk, a sequel to Mr Finchley discovers his England. It first appeared from Hodder and Stoughton in 1938 at 7/6 with a print run of 7,500, and there was an American edition by Carrick and Evans at $2.00 in the same year. It was reprinted in a cheap edition in 1940 with a print run of 4,000, was included in the Heinemann uniform edition in 1971 and reprinted in 1979 at £4.50. The new edition from Lulu.com is the first in paperback. It is also available as an e-book.
The dedication of the book is "To R. Percy Hodder-Williams and Ralph Hodder-Williams", two of the directors of the publishers. Canning must have been a considerable asset to them at this stage.
Canning claimed in a newspaper interview (Western Morning News, 26 Feb 1976) to have spent a year in France writing this novel and learning French, but in a private document he says "several months" and that is more likely. He certainly learned to speak French reasonably well, and seems to have had a real fondness for the country. His use of French in this and later books and short stories is accurate and careful but not very idiomatic. In the book the fact that Mr Finchley speaks a little French is accounted for by his having done some service in France during the Great War, which was true of Canning's father who spent the war as an ambulance driver in France and Flanders.
There was a dramatisation of this book and its sequel, Mr Finchley takes the road, broadcast on BBC Radio 2 in 1990. This was repeated in 2005 and again in 2008/9 and 2012 on the digital channel BBC 7, now called BBC Radio 4 Extra. Mr Finchley was played by Richard Griffiths (the actor who plays Mr Dursley in the Harry Potter films) and Mrs Crantell by Dinah Sheridan ("Mother" in The Railway Children). The script was by the father-and-son scriptwriting team of Eric and Andrew Merriman, distant cousins of Victor Canning.
A review in The Times of 9 July 1938 found it "rather too sentimental to be satisfying."