Europe is facing a wave of migration unmatched since the end of World War II - and no one has reported on this crisis in more depth or breadth than the Guardian's migration correspondent, Patrick Kingsley. Throughout 2015, Kingsley travelled to 17 countries along the migrant trail, meeting hundreds of refugees making epic odysseys across deserts, seas and mountains to reach the holy grail of Europe. The definite book on the rufgee crisis.