The team delves deeper into the secrets of the skilled communities who built medieval castles. The stonemasons working on the castle walls are dependent upon blacksmiths, whose metalwork was magical to the medieval mindset, and upon carpenters employing sophisticated geometry.Ruth Goodman, Peter Ginn and Tom Pinfold discover the ways in which every aspect of construction at Guédelon Castle requires the masons, blacksmiths and carpenters to coordinate their efforts - from making and sharpening tools to processing wood and securing timber scaffolding on the castle walls.A water mill has been built, complete with sluice gates and a network of waterways to power it. Water mills were hugely important to medieval communities. Producing flour for a loaf of bread required up to two hours of grinding grain by hand. But one mill could produce as much flour as around 40 people grinding by hand, thereby eliminating the daily grind. In England, as early as 1080, there were 5,624 watermills according to the Domesday Book. But there are major teething problems with the Guédelon mill, which Peter and Tom are helping to fix.A wooden walkway is also being constructed to connect the Chapel Tower with the Great Hall. The team follows every step of the process - from cutting down trees and shaping the wood through to the complex task of measuring up, before finally bringing the cut timbers into place around the stone walls of the tower.Ruth rewards the team with a pike supper - a medieval delicacy - and Tom uses flour ground at the mill for his very first attempt at making bread.