"Fey. Like in stories. 'Cept the stories get things mixed up." Rhia tugged Kaylee out into the street, and across it to a park. "See the little wall there?" She pointed at one of the low walls that deliniated the edge of this park. "Edge of the Doors are like that. With an arch or a break where you're allowed to go through. There are circles of 'em at home. Sometimes the Doors can be anywhere, though, when the fey want to get to someone quickly."
She looked up at Kaylee, beaming. "My Gran has one in Torchwood at home, so she can visit me when I'm staying with Uncle Jack. She doesn't have one where Dad and Mum and I live, though. It's rude to put a Door too close to somebody else's Hall."