Seven years after Monst-Apocalypse, Joel Dawson and the rest of humanity have been living underground since giant creatures took control of land. After making radio contact with his high school girlfriend, Aimee, who is 135 miles away in a coastal colony, Joel begins to fall in love with her again. Realizing that there is nothing underground for him, he decides to venture to Aimee, despite all the dangerous monsters that stand in his way.