What to read after Crooked House?

In a sprawling mansion in affluent Swinly Dean, Aristide Leonides lies dead from barbiturate poisoning. An accident? Not likely. In fact, suspicion has already fallen on his luscious widow, a cunning, much-younger beauty rumored to have been engaged in an illicit affair. But criminologist Charles Hayward, who' s in love with the dead man' s granddaughter Sophia, has his suspicions about the whole unsavory Leonides clan. Can he solve the puzzle without implicating Sophia? Christie considered this novel, dramatically read by Hugh Fraser, one of her best.