The Crossroads — John D. MacDonald

More than half a century ago, Papa Drovek opened his small grocery store at the junction of two country roads. As he bought more and more land, the roads became highways, and now the Droveks own a complex of hotels, restaurants, a truck stop, a shopping centre and two gas stations.

Papa's eldest son, Charles, is president of the Crossroads Corporation. His son Leo enjoys his token job, and daughter Joan manages the commercial tenants' leases. But when younger son Pete's wife gets restless and lonely, she becomes an easy pawn in a sleazy scheme of robbery and murder. The target? Old Papa Drovek himself.