Agatha Christie 
The Secret Adversary 

The Secret Adversary was written by one of the most famous and widely acclaimed mystery book authors in English, Agatha Christie. This novel is about a criminal investigator. It presents the characters of Tommy and Tuppence, who are featured in three other Christie books and one collection of short stories. The five Tommy and Tuppence books range from Agatha Christie's literary career. The Great War is over, and jobs are failing. Tommy Beresford and reasonable "Tuppence" Cowley meet and consent to start their own business as young adventurers. They are employed for a job that leads them both to various dangerous situations, meeting partners too, including an American millionaire in search of his cousin. A must-read book for all literature and mystery lovers.