With Trefelin under quarantine, supplies are getting low. Despite Prem's attempts to piece together the evidence, the real source of the outbreak is still unknown. As one-by-one the miners who played cards in Ceri's barn fall victim to the virus, it seems that Dan knows more than he is letting on about how he fell ill. Meanwhile, Megan is helping Emlyn keep law and order, and between them they come up with a plan to get more food from the next village. It seems that things are finally getting back to normal, until Mary arrives with some terrible news.