The Big Four: A Hercule Poirot Novel by Agatha Christie
Just finished this one today. I think it is one of my favorite Poirot stories. Lots of twists and cliff hangers, a quick and enjoyable read.
Hercule Poirot matches wits against the very powerful "Big Four". These four criminal masterminds have joined forces and have big plans (read: world domination). This is international intrique is not the typical Christie murder mystery. Poirot may have finally met his match and becomes desperate enough to call on his equally clever, but lazy, twin brother Achille. This is a fight to the death.