 In Chicago, we met with the Secret Service agent overseeing security for the Democratic National Convention in August. We're not only here to ensure the safety of the attendees of the convention, but there's almost 2.7 million residents of the city of Chicago that live and work here every day. Chicago's police plan to put hundreds of officers on bikes for crowd control. The city's top cop mindful not only of the threat of terror, but how crowds themselves can become a security threat.