May Contain Traces Of Magic by Tom Holt
There are all kinds of products. The good ones. The bad ones. The ones that stay in the garage mouldering for years until your garden gnome makes a home out of them. Most are harmless if handled properly, even if they do contain traces of peanuts. But some are not. Not the ones that contain traces of magic. Chris Popham wasn't paying enough attention when he talked to his SatNav. Sure, she gave him directions, never backtalked him, and always led him to his next spot on the map with perfect accuracy. She was the best thing in his life. So was it really his fault that he didn't start paying attention when she talked to him? In his defence, that was her job. But when 'Take the next right' turned into 'Excuse me,' that was when the real trouble started. Because sometimes a SatNav isn't a SatNav. Sometimes it's an imprisoned soul trapped inside a metal box that will do anything it can to get free. And some products you just can't return.