Sins of the Fathers by Susan Howatch

Full of fascinating dialogue, surprising twists of plot, and well-developed, memorable characters, a stunningly successful work of fiction.
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This is the tumultuous novel of men and women pitted against a world of wealth, power, and privilege...the story of the powerful Van Zale clan, and the man, Cornelius Van Zale, whose dynastic struggle to control a great fortune becomes the center of his life. When the world of the Van Zales, of servants and country houses, of European summers and Bar Harbor clambakes, polite marriages and discreet affairs, suddenly begins to fall apart, we see this glamorous sphere for what it really is--rife with ruthless, power-hungry men, fortune hunters, secret sex, blackmail...and violence.