Big Four

The book is often praised for its unique departure from Agatha Christie's typical whodunit mysteries, venturing into the realm of international espionage and thriller genres. Readers found the ambitious scope and global implications of the plot to be a refreshing change, with some noting Christie's surprising foresight in incorporating concepts like advanced wireless technology and atomic energy for a 1927 novel. The narrative offers a fast-paced, action-packed experience, which some reviewers found highly entertaining and a "wild ride." Moments of warm and humorous interaction between Hercule Poirot and Captain Hastings are highlighted, and some appreciate seeing a more human and fallible side of Poirot, making him more relatable. Despite its unconventional nature, many still found the plot to be intriguing and well-constructed, making for an enjoyable and thrilling read.

However, a significant number of reviews criticize the book's structure, widely attributing its disjointed feel to its origins as a collection of short stories loosely stitched together into a novel. This results in a narrative that often feels messy, with an abundance of characters appearing and disappearing, and frequent, sometimes confusing, changes in location. Many readers expressed disappointment with Poirot's atypical portrayal, finding his involvement in fighting supervillains with disguises and gadgets to be out of character and stretching credulity. The antagonists themselves, a global cabal of four masterminds, are often deemed underdeveloped, lacking clear motives, and their overarching plot for world domination is considered far-fetched and unrealistic. Some reviewers also pointed out uncomfortable racial undertones in the depiction of certain characters and found the dialogue and overall writing quality to be below Christie's usual standard, leading to a less satisfying reading experience.

Ultimately, this book receives a very mixed reception, standing out as a divisive entry in Christie's bibliography, with some even citing Christie's own negative reflections on it. While it may not be considered one of her best works, its unconventional nature offers a different kind of entertainment. It is generally not recommended for new readers of Agatha Christie or those seeking a classic Poirot murder mystery. Instead, it is best suited for hardcore Poirot fans and completionists who are interested in exploring the full range of Christie's work, including her experiments with other genres. Readers who enjoy spy thrillers, international intrigue, or a more action-oriented narrative, and who are willing to approach the story without taking it too seriously, might find it an amusing and unique addition to the series.