What is the plot of the big four by Agatha chrisite?

"The Big Four" by Agatha Christie follows detective Hercule Poirot as he investigates four crime lords who form an international crime syndicate. Poirot must unravel a complex web of deception and intrigue to solve a series of murders and thwart the criminal organization's plans. The novel explores themes of power, greed, and the battle between good and evil.