Prologue

Count Sergei Pavlovich meets in Paris with the Russian dancer Nadine. They both work for a certain Colonel engaged in espionage. The colonel decided to retire, and they are afraid that they will be left without work. Once, Nadine helped the Colonel in an adventure with diamonds, several stones remained with her, and the woman expects to blackmail their boss. Nadine also hopes for the help of her husband, who is supposed to come from South Africa.

Novel

After the death of her father, the largest specialist in primitive people in England, Anna Beddingfeld is left without a livelihood, since his scientific works did not bring income. Dreaming of adventure girl arrives in London. On the subway platform, she sees a man who smells strongly of mothballs. Suddenly, a man falls with an expression of horror in his eyes. A person emerges from the crowd who presents himself as a doctor and ascertains death. In what is happening Anna sees something unnatural. She picks up a piece of paper that the doctor defended. On a piece of paper, also smelling of mothballs, it says "17.1 22 Kilmorden Castle".

It turns out that the deceased was called L. B. Cardboard, and he arrived from South Africa. In his pocket they find a warrant to inspect the Mill House for rent owned by Sir Eustace Pedler. Anna’s testimony that Cardboard was frightened of someone is not taken into account, and the doctor does not come to the police. The next day, a dead woman is found in the mansion. Through a real estate agency, a certain Mrs. Castina came to inspect the house. She left her address at the hotel, but it turned out that there was no such lodger. The servant gave her the keys, but did not accompany the woman. A little later a young man appeared in a brown suit, who called himself a friend of Mrs. Castina. Soon the man left very upset and said that the house would not suit them. The next day, the woman was found strangled. Suspicion falls on a man in a brown suit.

Anna believes that the person who examined the corpse in the subway was not a doctor, his actions were too unprofessional, but the police inspector did not listen to her. The description of his appearance to the inspector does not say anything, all this can be easily changed with the help of makeup. Anna draws attention to a detail that cannot be changed: the doctor has a brachycephalic head shape.

Anna asks for the place of a special correspondent for investigations in the editorial office of one large newspaper, because she has information, but she is refused there. Then the girl takes a warrant from a real estate agency and arrives at Mill House. Looking around the room in which the murder took place, Anna finds an empty photographic film smelling of mothballs. The girl suggests that the “man in a brown suit” and the doctor are the same person. He pulled the tape from the deceased and then lost it in the house. Anna sees an advertisement for the Kilmorden Castle ship, which sets sail on 01/17/1922 and buys a ticket for all its savings.

Sir Eustace calmly accepts the news that a woman was killed in his house. In Parliament, he is informed that problems are brewing in South Africa, and Sir Eustace needs to go there. An assistant is sent to him - a young man Harry Rayburn. For security reasons, Harry asks not to tell anyone that he is accompanying Sir Eustace.

On the ship, Anna is studying passengers. Her attention is attracted by the famous aristocrat Lady Susanne Blair, special services officer Colonel Reis, Sir Eustace Pedler and his assistant Guy Paget (Harry Rayburn is not feeling well because of the pitching and lies in the cabin) and the Rev. Edward Chichister. One day, Susanna accidentally drops a box of film on the lower deck.

At one of the stops, several cabins are freed, and Anna wants to go to the cabin number 17, where she is not so sick. But this cabin is claimed by Sir Eustace, Guy Paget and Edward Chichister. After disputes, the cabin goes to Anna. In it, the girl smells a strong smell and understands that they want to expel her from there. Remembering the note with the numbers, she compares them: 17.1 22 do not mean the date, but the cabin number, time and day of the month.

At one o’clock in the morning a young man, wounded under a shoulder blade, rushes into the cabin and asks him to hide. A maid enters the cabin immediately and asks if everything is in order, as a drunken man runs around the vessel and runs into the cabins. Anna bandages a man’s wound and he leaves. The next day, Anna notices that someone was searching her cabin.

Those who wanted to occupy the seventeenth cabin fall under the suspicion of the girl: Sir Eustace, his secretary Mr. Paget and Rev. Edward Chichester. Chichester does not impress Anna as a priest, says he lived in South Africa, but there is no African tan on him.

Sir Eustace picks up a piece of paper defended by Chichister, which says that he does not try to play alone.

Colonel Reis talks about his relative, Sir Lawrence Erdsley. Sir Lawrence's son John and his friend Harry Lucas have found the richest deposits of diamonds in South Africa. At this time, a robbery broke out at the diamond sending company, and John became suspicious because jewelry was found in his belongings. The father was able to help his son out, but John died in the war. Father died without surviving his death. Harry Lucas also fought, but went missing. Colonel Reis became heir to Sir Lawrence. Upon hearing the story, Rayburn changes face. Finally seeing Rayburn, Anna notices that it was he who was in her cabin.

Anna learns from the steward of the ship that the maids do not work at night, only the stewards. Girl shares information with Suzanne Blair. The aristocrat decides that at night a man dressed as a maid, most likely Chichister, entered the cabin of Anna. Looking at the note, Suzanne notices that there is not a dot on the piece of paper, but a speck, and the cabin may not be 17, but 71, that is, it. She learned from the assistant captain that the cabin was ordered for the ballerina Nadina, the agent of the leader of the gang operating in Europe, a certain Colonel. Anna realizes that Nadina and Mrs. Castina, who was killed, are one and the same person. Suzanne threw a box from a film with diamonds out the window in the middle of the night. From the shape of her head, Anna realizes that the man is in a brown suit, he is a doctor - this is Rayburn. He entered the house immediately after Nadina, therefore, he did not kill her. The killer was already in the house, or entered there in another way. Cardboard and Nadina were supposed to meet there. Anna admits to Suzanne that she fell in love with Rayburn.

The ship’s steward, already familiar to Anna, says that on the way to England, one of the passengers, Cardboard, handed him a film and told her to drop it on January 22 into cabin No. 71, where the woman was supposed to be.

From a conversation with Paget, Anna realizes that during the murder he was in the house of Sir Eustace. Together with Suzanne, they are developing an action plan. Tomorrow everyone leaves the ship. Chichister goes to Durban, and Sir Eustace to Cape Town. Susannah, who was invited by Sir Eustace, wants to persuade Colonel Reis to join them.

Rayburn saves Anna from Paget's attack. Anna tells Rayburn that she knows his real name - Harry Lucas, and that he is "a man in a brown suit." Rayburn warns Anna not to get involved in dangerous games. Perhaps not only she knows this.

The battered Paget says to Sir Eustace that Rayburn attacked him. It seems to Paget that Rayburn and Flight are up to something. Sir Eustace inquires and finds out that no one was sent to him from Parliament.

In Cape Town, Anna and Susannah stay at the hotel. Anna unexpectedly receives a note from her father's old friend. The girl arrives at the specified address and falls into the trap. She is tied up and left in the attic.Anna manages to unravel the ropes and going down, she hears the one who tied her, talking to Chichester. They are both waiting for the Colonel to speak with the captive. Confident that the captive lies bound, they leave. Anna runs away and meets Susanna. Women are joined by Colonel Reis, who reports that Rayburn is "a man in a brown suit." They did not have time to arrest him, he disappeared.

Leaving Paget in Cape Town, Sir Eustace travels to Rhodesia. He offers Anna to work as his secretary, but she wants to stay in order to follow Paget. With the help of Susanna, Anna deceives Paget, says that she is leaving for Durban. But the girl feels that some man is chasing her. She also notices that the stranger is talking with Paget. Frightened, Anna decides to leave with Sir Eustace and Suzanne. At the last minute, she jumps into their train. Sir Eustace had already hired a secretary, Miss Pettigrew, a tall square business woman, about forty years old. On the way, Anna tells Sir Eustace that she works as a correspondent in a newspaper and tracks down a "man in a brown suit." Sir Eustace is amazed that Anna guessed who the murdered woman was.

In Rhodesia, Suzanne and Anna buy many wooden souvenir toys. Colonel Reis confesses love to Anna, but the girl refuses him, she can not forget Harry Rayburn. Suddenly she receives a note from him in which he makes an appointment.

In the indicated place, Anna falls into the abyss. Harry Rayburn finds the girl and brings him to his house on the island. Harry found her by accident. He did not send any note.

Anna remains on the island. Harry confesses her love, but he is afraid to ruin the girl's life. He tells Anna that he and John Erdsley were lucky, they found diamonds, but met actress Anita Grünberg, and both fell in love with her. Hiding from friends that she was married, Anita changed diamonds, and now they are both disgraced. John died in the war, and Harry lives here under a false name, although it is believed that he was missing. One day, while riding tourists on a boat, Harry met a man who panicked him. It was a certain Cardboard, Anita’s husband, working in a diamond shipping company. Cardboard said that Anita works for a certain Colonel, but the Colonel also participated in the robbery, and Anita, now called Nadina, believes that she is holding him on a hook.

Upon learning that Cardboard was traveling to London, Harry followed him. In London, Harry found out that Cardboard had met his wife, and they were planning on renting Sir Eustace's house. Watching Cardboard, Harry entered the subway. Seeing him, Cardboard fell in fear from the platform. Then Harry passed himself off as a doctor and, taking advantage of this, took the contents of Cardboard pockets. Then he followed Nadina, but found her strangled in the house of Sir Eustace. Upon learning that Sir Eustace was going to South Africa, Harry hired him to work. Now Anna and Harry suspect Paget of murder, because he was near the mansion that day.

Harry decides to send Anna to his friends, but during the crossing on the boat they are bombarded. Harry sends Anna to his friend who will help her. Before parting, they agree on conventional signs in correspondence so as not to fall into the trap again.

Colonel Reis and Suzanne became alarmed over the disappearance of Anna, but Sir Eustace does not attach any importance to this and, according to his own affairs, goes to Johannesburg. Suzanne asks him to help send baggage with souvenirs purchased.

In Johannesburg, riots are taking place in connection with the strike. Sir Eustace meets Colonel Reis. Suzanne sent him a telegram that Anna was back, and she was fine. The colonel also reports that Harry Rayburn's real name is Harry Lucas, and they have an affair with Anna.

Anna meets with Paget, and he reveals her secret to her: he has been married for four years and has four children, but is forced to hide his marriage, since the personal secretary must be single.Paget's wife lives near the Mill House, and he went to see her because she was expecting a baby at that moment.

Anna receives a telegram signed by Harry, in which he asks her to go to Johannesburg. The paget meets Sir Eustace and reports that a man is visiting Miss Pettigrew, and shaving accessories are found in her room. Paget believes that Miss Pettigrew is a disguised man. Paget also reveals his secret to Sir Eustace.

In Johannesburg, Anna finds Edward Chichester, who was hiding under the name of Miss Pettigrew, at the indicated address. Anna falls into his trap a second time. He escorts the girl to his boss, Sir Eustace, who is Colonel. Anna had guessed this earlier when Paget told her that when visiting his wife he saw Sir Eustace, although he was supposed to be in another place. It was he who wanted to drop Anna from the ship, and Paget accidentally appeared nearby. Sir Eustace organized an uprising in the city, supplying weapons. Now he wants to know where the diamonds are and demands that Anna return them in exchange for life. Anna says that the diamonds are with Harry and sends him a telegram asking him to bring the diamonds to the address indicated.

Sir Eustace tells Anna that Nadina threatened to hand over diamonds to Harry. He knows who Harry Rayburn is, and took him to his work, hoping that he has diamonds. The agent of Sir Eustace Chichister, who turned out to be an actor of Minks, tried to play against the boss, but Sir Eustace reasoned him. Sir Eustace tells Anna that he has diamonds. He opened all the luggage boxes and took away all the boxes of film that were there. Then Harry bursts into the house and says that Sir Eustace is surrounded. Upon receiving the telegram, Anna knew that she was false, since she did not match their cipher with Harry. She informed him and Reis where she was going. Sir Eustace offers Harry a deal: he will write a confession that he killed Nadina, and Harry will let him hide. But Minks, who met with Nadina under the name of the Russian count, has evidence of the guilt of Sir Eustace, and he will testify against him. Diamonds are not in the box from the film, but in one of the wooden toys.

Sir Eustace manages to escape through a secret passage, and Harry Rayburn admits that his real name is John Erdsley. During one of the fights, he and Harry Lucas switched signs, and Harry was killed in that battle.

Two years have passed. Sir Eustace is located somewhere in Bolivia, Susannah was carried away by psychoanalysis, and Paget had a sixth child. And John Erdsley took Anna to the island, and they have a son with chocolate skin from the African sun, truly "a man in a brown suit."