The Crossing, a short story

Conrad and Margot, having driven the length of Mexico from the States with two small children, are crossing the border between Mexico and Guatemala at Christmas time. He has hunting weapons, and permits from all the interveneding countries to carry them into Costa Rica. An incident in Guatemala has caused all gun permits to be canceled, and something strange has happened to the colonel who signed the gun permit—he doesn't exist any more. What would have been a lengthy process at that time of year, turns into a day-long ordeal.