Area of Suspicion — John D. MacDonald

Four years ago Gevan Dean found his fiancée Niki Webb in his brother Ken's arms and fled his hometown for a peaceful life in the Florida sun. But now Ken is dead - murdered by a thief, the police say - and Gevan is desperately needed to keep their company, Dean Products, from falling apart.

Everywhere Dean turns he finds only questions and confusion. But he doesn't suspect the truth behind Ken's murder or the real goings-on at Dean Products until the stakes get too high to ignore - and the truth explodes violently in his face ...