This week, The Cipher Brief looks back at five groundbreakers in the national security space. Each in his/her own right has blazed a trail for others to follow — in policy, spycraft, and law enforcement. From Pentagon pioneer Michele Flournoy to Steve Murphy, who co-led the demise of Colombian drug lord Pablo Escobar, take 15 Minutes to hear from some of the leaders and change-makers in national security and intelligence. To listen to the full podcasts with each of these trailblazers, search The Cipher Brief podcasts.