Still good — but not as good as earlier Christie, in my opinion.

The Big Four is a secret international crime cartel with 4 leaders who want to dominate the world.

Claude Darrell, known as the Destroyer, is worst of the worst. He dies when their hidden lair of the Four explodes — or did he?

Perhaps the book seemed less precise because it evolved out of 12 short stories.

Others speculate that this novel was assembled at a low point in Christie’s life. She was arguing with her husband. They were soon to be divorced.

In fact, at one point in 1926 she disappeared for weeks. More than a thousand police officers, 15,000 volunteers, and several aeroplanes searched the rural landscape near where her car was found.

Eventually she was discovered in a hotel under an assumed name.