A plot to kill a Labour MP and a police officer was only disrupted after an informant within the neo-Nazi group National Action blew the whistle. Robbie Mullen passed the details on to Hope Not Hate’s Matthew Collins. Here, they tell their extraordinary story. Also today: the columnist Aditya Chakrabortty on his unlikely collaboration with the techno group Underworld. Help support our independent journalism at theguardian.com/infocus