It is bread week, and Paul Hollywood has put together three of the toughest challenges ever. First up is the signature challenge - a sweet dough with a twist. And with Paul's digits primed for prodding, no dough is safe from scrutiny.The bakers then face a steamy technical challenge without an oven, as Paul and Mary step out of the tent to leave the bakers with only a basic set of instructions and ingredients. For the perfect bake they have to avoid a burnt bottom and a soggy top.Mel heads to Germany to discover how one brave baker and a few hundred dumplings saved his small town from the ravages of the Thirty Years' War.And there is a mighty final challenge which requires the use of three different flours to create a huge showstopper centrepiece.