"A Difficult Problem 1900" is an exciting detective novel by the famous American writer Anna Catherine Green. In this book, readers are sent to the era of the beginning of the 20th century, where crimes and mysteries are intertwined with the worlds of high society and police investigation. The main character, a resourceful detective, is faced with an extremely difficult task that seems hopeless to solve. Convoluted storylines, unexpected turns of events and sophisticated psychological analysis of the characters make this book exciting for lovers of the detective genre. "Complex Problem 1900" is an exciting journey into the world of mysteries and investigations, where each of the heroes has his own dark secrets and unresolved questions. The author successfully combines tension, intrigue and unpredictability to leave the reader in tense anticipation of the solution to the last puzzle of this complex problem.