Using cutting-edge research, a dedicated team of archaeologists has compiled the evidence to fill in a 400-year gap in man's knowledge of the bluestones of Stonehenge. By combining innovative 3D scanning techniques, traditional field archaeology and novel laboratory analysis, the team has discovered where the stones were quarried and where they first stood. Professor Alice Roberts shows how the team made its discoveries and joins Professor Mike Parker Pearson to piece together the final parts of the puzzle, solving one of the toughest challenges ever faced by archaeologists.