From the brilliant pen of Agatha Christie comes two novels featuring the beloved sleuthing duo: In the The Secret Adversary, Tommy and Tuppence decide to embark on a daring business scheme: Young Adventurers Ltd. But they get more than they bargained for when their first assignment for the sinister Mr. Whittington draws them into a diabolical conspiracy. Set during the dark days of World War II, Agatha Christie’s N or M? puts two most unlikely espionage agents, Tommy and Tuppence Beresford, on the trail of a pair of Nazi spies who have murdered Britain’s top agent.

Mr. Shaitana is famous as a flamboyant party host. Nevertheless, he is a man of whom everybody is a little afraid. So when he boasts to Hercule Poirot that he considers murder an art form, the detective has some reservations about accepting a party invitation to view Shaitana's "private collection". Indeed, what begins as an absorbing evening of bridge is to turn into a more dangerous game altogether.

It had been a typical New Year's Eve party. But as midnight approaches, Mr. Satterthwaite - a keen observer of human nature - senses that the real drama of the evening is yet to unfold. And so it proves when a mysterious stranger knocks on the door. Who is this Mr. Quin? Mr. Satterthwaite's new friend is an enigma. He seems to appear and disappear almost like a trick of the light. In fact, the only consistent thing about him is that his presence is always an omen - sometimes good, but sometimes deadly....

Mrs. Packington felt alone, helpless, and utterly forlorn. But her life changed when she stumbled upon an advertisement in the Times that read: "Are you happy? If not, consult Mr. Parker Pyne." Equally adept at putting together the fragments of a murder mystery or the pieces of a broken marriage, Mr. Parker Pyne is possibly the world's most unconventional private investigator. Armed with just his intuitive knowledge of human nature, he is an Englishman abroad, traveling the globe to solve and undo crime and misdemeanor.

When Hercule Poirot, a well-known inspector and an eccentric, but very likable, Belgian refugee from the Great War, discovers that Emily Inglethorp, his wealthy benefactress who helped him through his new life, has been found dead, poisoned with strychnine, he sets out to solve the crime. But there is a problem. The main suspects are close relatives who can't or don't want to cooperate.