The gruesome murder mystery of 39 battered skulls found underneath a London bookshop

Roman ship and cargo, London, 1st-3rd century. An artist's impression of a ship carrying ragstone at the entrance to the Fleet River. The remains of such a boat were found in the River Thames at Blackfriars. The stone it was carrying may have been intended for the building of the city wall, parts of which are still visible today (Image: Getty Images)