"Generator room," John supplies softly. "There are four generators spread out across the city. This one is the one I deactivated to kill control to command, so they couldn't track me."

He approaches a large, glowing silver object that looks oddly like a futuristic bomb and hesitates over it.

"They kick out a lot of power," he adds awkwardly. Which means yes, they are dangerous. He reaches out, takes a steadying breath and carefully removes a central pin. It goes dark, and he glances around the room expectantly before stowing it. It's quieter without the hum of it working, and the room is dark. "That's one down."

There's still three more active, though. He scans the shadows warily with his gun, lofts an eyebrow questioningly at Ianto.