The mysterious Roopkund lake, a place in the Himalayas located 5 thousand meters high and surrounded by rock glaciers. One month a year, always at the same time, when the glacial lake is due to thaw.
Hundreds of human remains, skeletons mixed with pieces of meat and hair preserved by the area's dry and frozen climate. DNA evidence indicated that there were two distinct groups of people, one a family or tribe of closely related individuals, and a second somewhat smaller group.