Chris and Xand van Tulleken - doctors, part-time aid workers and twin brothers - want to see for themselves what conditions are like for migrants fleeing through Europe at the height of winter. They travel to Lesbos in Greece, through the Balkans and on to Berlin and Calais to understand what's being done on a medical and humanitarian level in response to the refugee crisis. Spending time with medics, charities and volunteers in camps and clinics, at border crossings and transit points, they find out what the situation is like on the ground and, wherever possible, lend a hand in the biggest migration crisis of our times.