As we mark five years after Europe's refugee crisis, we revisit our episode with Boris Cheshirkov, who worked for UNHCR as a spokesperson in his native Bulgaria when thousands of refugees were arriving at the border. It was an extremely tense time, testing European solidarity to its limits - bringing out the best of humanity and also the worst.

Anti-refugee feeling was running high. In Bulgaria, an asylum seeker was shot dead at the border. But when Boris spoke out against the violence, he himself became the target of a virulent online hate campaign. The threats were so severe he had to leave his country. Boris now serves in Greece, where refugees remain in limbo.