High society takes a tumble in the A&E program City Confidential: Dallas -- Arsenic and Old Money. As home to wealthy oilmen and upper-class businessmen, Dallas enjoys an international reputation for excess. The exclusive settlement of Park Cities houses many of the Texas well-to-do. That's why Nancy Lyon's death came as such a shock. When it was discovered that she died from arsenic poisoning, the scandal deepened. In a case of the in-laws versus the husband, Richard Lyon was accused of the murder. At his trial, Park Cities' residents found out much more than they ever anticipated about an unhappy marriage, a suicidal wife, and a motive to kill. ~ Sarah Ing, Rovi