The Gateway Arch in St. Louis, Missouri is a 630-foot monument to Western expansion in the United States. It overlooks a city known for its barbecue, blues music and art. It's a modern marvel to behold. At night, the Arch holds sway over the darker side of the city. Nightclubs, dimly lit bars and people leading secret lives takes place in its shadows. Sometimes, the criminal element comes out to play. If you're not careful, you might...