It’s dawn in the Aegean Sea. A dozen asylum seekers are crammed into a rubber dinghy, hoping to land on the Greek island of Lesbos. They are already within EU waters — and they have the right, under international law, to claim asylum. But a huge ship is blocking their way. This week we are looking at the phenomenon of pushbacks: illegal efforts to push people back across a border so that they cannot claim asylum. And we’re looking at mounting evidence that the EU’s border agency, Frontex, has witnessed or even participated in these pushbacks.