The Last Zephyr

America's most scenic train, The Zephyr, is deep inside Moffat Tunnel when the entire Yellowstone Caldera explodes, spreading death and destruction across the west. While millions die, the passengers and crew aboard the Zephyr are protected in the 6.2 mile long tunnel. As ash settles, the people on the train have to use all of their combined wisdom, skills, and resources to punch their way out of the mountains, get clear of the dead zone, and survive together on the Last Zephyr.