The terror attack in the New Zealand city of Christchurch appalled the world. The indiscriminate murder of 50 Muslim worshippers during Friday prayers was calculated to spread fear and a message of right-wing terror. Four Corners investigates how the Australian born killer was able to operate under the radar. His plot was intricately planned, harnessing the tools and the power of the internet to amplify the terror to a global audience. The program investigates whether authorities have been so focused on Islamic extremism that they’ve failed to grasp another deadly threat, the rise of far-right white supremacists.