When the power mysteriously goes out across the country, society does not instantly break down. Transportation does. Most people simply wait. Martin thinks trouble is coming. His Plan B is to walk the 50 miles from Boston to his home in New Hampshire. His plan B must be revised. He did not plan on Susan: a woman he only knew as a teller in his bank. Traveling together, they encounter criminals out to exploit the outage and local governments intent to restrict travel.