It's the semi-final, so the briefs and the judges are tougher than ever. Four previous winners are back to redesign a reception room each in Edinburgh's historic tenements, but only two can go through to the final. With higher stakes comes a higher budget, as each designer has £1,500 and three days to convince the judges that they deserve a place in the grand final. Our first designer must prove they can stamp their own identity on the room. Designer number two must show they can deliver creativity in a scheme, but plans for pimping up some flat-pack furniture fall flat with the clients. Our third semi-finalist needs to impress while working to a traditional brief. Meanwhile, our final designer is working to a mid-century brief but could be derailed while creating a giant lampshade out of wool. Architectural historian Tom Dyckhoff examines the history of the tenements in Edinburgh and the secrets that enticed the Victorian middle classes to live here. Meanwhile, judges Sophie Robinson and Daniel Hopwood have the difficult task of deciding which two designers have what it takes to make it through to the grand final.