Linguistic confusion and mass killers

Kate Adie introduces correspondents' stories. Damien McGuinness is in Berlin where the politicians are frustrated that British politicians don't seem to understand that no means no. Jake Wallis Simons returns to the scene of the terrorist attacks in Paris last year. James Jeffrey is in Addis Ababa, under a state of emergency, where there's confusion about what really is going on but people are partying as hard as ever. Lindsay Johns travels from Harvard to Harlem in a divided America. And Chris Carnegy meets one of the world's most prolific killers, in the South Atlantic. But his targets are mice.