Historian Guy de la Bedoyere asks the team to investigate the isolated ruins of a bath-house, discovered by Gerald Brodribb in the midst of dense Sussex woodland. Gerald has made a scale model of the building, and Guy explains the connection to the Roman navy. After a demonstration of dowsing from Gerald, the team's first task is to clear the land before digging. With ancient technology expert Jake Keen and blacksmith Reg Miles, Phil attempts to smelt iron using a traditional furnace. The team are also joined by archaeometallurgist Gerry McDonnell.
