Time Team examines a mysterious cave in Derbyshire where cavers have found several skeletons, some of them newborn babies and the earliest dated to the Stone Age. Finds from the cave have also provided dates from the Iron Age and the Roman period. The excavation proves potentially quite hazardous, as the chambers and tunnels are filled with precariously heaped stones which threaten to scree if the safety shoring moves or breaks, and some areas are considered just too unstable to work in at all. The archaeologists also investigate a nearby Bronze Age barrow, which previously has been subject to illicit excavation. In the cave they find more human and animal remains, although how these got there remains subject to some debate. The mound gets confirmed as a barrow and undisturbed secondary burials are discovered as part of the structure.