Fourth Side of the Triangle — Ellery Queen

A fashion designer's murder draws legendary sleuth Ellery Queen into a New York society family's tangled web of secrets.

Ever since New York was Nieuw Amsterdam, the McKells have been building their fortune. Combining Scottish thrift with American know-how, they built an empire that, by the 1930s, stretched across the globe. No one in the family found more success than Ashton McKell, an entrepreneur who counts his wealth in the hundreds of millions, who smokes twenty cigars a day, and whose only problem is his son Dane, an adventurous soul who shocks his father by giving up business for the disgraceful pursuit of writing. Despite their differences, Dane loves his father. He is shocked when he learns the old man is having an affair -- and thunderstruck when Ashton is accused of murder.
 
When his father's mistress is found dead, Dane will do anything to free Ashton. And no detective is more suited to this puzzling case of blackmail, lust, and greed than the singular Ellery Queen.