During the coldest winter ever, George and Gracie land in Menlo Park, New Jersey, 1879--near Thomas Edison's famous laboratory. Mr. Edison has just invented a long-burning light bulb, but he's keeping a huge secret: he's also discovered time travel. In fact, he built his own time machine. The kids get an even bigger surprise when a young Mr. Crowe walks into Edison's laboratory--as his assistant The older and dangerous Mr. Crowe is sneaking around...