“We don’t really think of those today, because it’s so convenient to go to the supermarket,” he cautions. “But you know, you’re planning because the supermarket may not always be there.”

The electrical grid could fail tomorrow, he frequently warns. Food would disappear from the shelves. Water would no longer flow from the pipes. Money might become worthless. People could turn on each other, and millions would die.

Such concerns are typical among “survivalists,” a loose national movement of individuals who advocate self-sufficiency in the face of natural or man-made disasters, gathering online or in person to discuss the best ways to prepare for the worst.

What is atypical is that the owner of this cabin is Roscoe Bartlett, the longtime Republican congressman from Maryland. Over the past two decades, he has developed a following as one of the country’s premier proponents of preparedness against impending doom, even urging the more than 80 percent of Americans who live in urban areas to relocate.

“There are a number of events that could create a situation in the cities where civil unrest would be a very high probability,” Bartlett predicts in “Urban Danger,” a documentary that features the cabin tour. “And I think that those who can and those who understand need to take advantage of the opportunity when these winds of strife are not blowing, to move their families.”