At Château de la Boutinière, after five years of hard work, this once-abandoned and graffiti-covered shell prepares to host its biggest ever wedding. But with just days to go, Alison and Zion race to get every final detail right. In the Loire Valley, at Château de la Croix Boisée, Vivienne and Simon strike up the overture for a retirement party worthy of Vivienne's opera-singing mother, but their terrace is still far from centre stage. And in Normandy, Xavier and Tasha finally get the keys to their dream home