What did the mystery dinner guest do to anger the children

The mystery dinner guest, Jeffrey Magee, angered the children when he ran atop the steel rails of the railroad track.

The Pickwell kids dashed out the back door to the top of Rake Hill. They scanned the railroad tracks. There he was, passing Red Hill, a book in his hand. He was running, passing the spear field now, and the Pickwell kids had to blink and squint and shade their eyes to make sure they were seeing right -- because the kid wasn't running the cinders alongside the tracks, or the wooden ties. No, he was running - running -- where the Pickwells themselves, where every other kid, had only ever walked -- on the steel rail itself!