Rhys Williams investigates the deadly rail disaster in Greece in February, when an InterCity passenger train collided head-on with a freight train, killing 57 people. He meets victims, bereaved families and those in the industry who issued multiple warnings in the lead up to the disaster. Chloe Keedy is with the Sami people of the Arctic North, where a commitment to green energy is disrupting an age-old way of life. In a Mexico City suburb, Rageh Omaar visits the altar of 'Santa Muerte' or Holy Death, a 21st century deity that accepts and nurtures the outcasts who feel neglected and rejected by mainstream religion.