Why did Greenland's Vikings disappear? The Vikings of Greenland left no clues to their sudden and mysterious disappearance. Or did they? On a desolate coast of Greenland, an international team of archaeologists, forensic anthropologists, entomologists and botanists sets out to investigate clues in a complex chain of events that may have led to the demise of a Viking colony. Unearthing the ruins of a settlement that included a cathedral complete with stained glass, the scientists carefully identify and date the vestiges of the Viking society. Among their discoveries are a "mini Ice Age," a war with neighboring Inuits, and a religious order that may have doomed the Vikings to obsolescence. (UK/PBS 55 min)