"Oh, she would definitely rip your throat out if given half the chance," Ianto replies easily. "That's why she's in the cells, she was one of the first to go rogue. There's a whole colony of then under the streets of Cardiff, in the sewers. They eat -- well pretty much anything you can imagine you might find in a sewer, really." He glances aside at the other man. "It's the ones who venture out and develop a taste for human flesh that we had to keep on the watch for."

He studies the photograph for a moment, before continuing, "You know, they're actually quite intelligent. And telepathic, near as we can figure. And empathic. They can..." He hesitates, debating how much to explain about this moment in time, before deciding, "They know when another of their kind is suffering. So we try to keep them as comfortable as possible in the cells, once they become a danger to the public as a whole." He shrugs. "I suppose they understand that it's better than the sewers, anyway."