On the 15th of April, in the worst terrorist attack on American soil since 9/11, two homemade bombs exploded at the finish line of the Boston Marathon, killing three people and injuring more than 200 participants and spectators. With interviews with those who knew them, Panorama reporter Hilary Andersson explores how the two suspected bombers - brothers raised and educated in the US - became radicalised, and asks if America's war on terror has come home. With the surviving brother due to stand trial later this year, she goes on patrol with New York Police Department's anti-terrorist squad which uses the latest technology to protect New Yorkers from future terrorist attacks. But she finds a backlash amongst many Muslims in America against law enforcement programmes they believe are designed specifically to profile, map and spy on Muslims. Panorama asks: are the authorities spying on the right people?