The Secret Adversary by Agatha Christie

The Lusitania was sinking after being struck by two torpedoes. A man approached the young American Jane Finn and asked her if she would take papers which were important to the war effort which had to be saved. He did this because he believed that women would be saved first from the sinking ship. He told her that if he survived he would contact her. If he did not, she should contact the American embassy. Jane Finn and the papers were not seen again.

Now the war is over. Prudence Cowley know by her friends as Tuppence encounters her old friend Tommy Beresford on a London Street. Both had just been demobbed, both were young, and both were looking for a job. They put there heads together and came up with the idea of joining forces to become the Young Adventurers who would take any job as long as the pay was good.  They would put an advertisement in the paper. Tommy mentioned the strange ads he had read, and the strange name of Jane Finn that he had just overheard two men talking about.

A man in the tea shop where they were talking overheard them and approached Tuppence on the street. He suggested that she come to his office, and discuss doing a job for him. Tuppence did so, and when asked her name thought it a good idea to have a pseudonym and gave the name Jane Finn. This name set the man, Mr. Wittington,  off in a rage. He suspected that Tuppence knew far more than she was telling him. He paid her fifty pounds and they agreed to meet the next day. However, the next day, he had disappeared.

This is the way that Tommy and Tuppence's adventure began. They placed an ad in the newspaper seeking information on Jane Finn. They got one reply from Mr. Carter who seemed to represent a British government department seeking information about Jane Finn.  They also got a reply from Julius P. Hersheimmer, a young American millionaire who said that Jane Finn was his cousin, and that he had come to England to find her.

Their search for Jane Finn would place Tommy and Tuppence in a great deal of danger as they found out that the papers Jane had would be very dangerous to the future of the English government if they fell into the hands of a mysterious Mr. Brown who was plotting a Communist conspiracy to attack the government and call a general strike of workers. Tommy and Tuppence received help in their efforts from Mr. Carter and Julius Hersheimmer, and also from a very distinguished and well known lawyer, Sir James Peel Edgerton, who some thought would some day become prime minister.

This book is a fun read, though there are several clues along the way to the real identity of the mysterious Mr. Brown which should enable the reader to solve this mystery before Tommy and Tuppence do. The book was published in 1922, and thus a very early Christie. It is the first of the Tommy and Tuppence series. A recent adaptation (2015) of The Secret Adversary is now streaming on Acorn TV. It has been updated to after World War II, and bears some faint resemblance to the original novel.