In 1980s Washington state, USA, Mount St Helens is rumbling. Twelve-year-old Maribel isn't concerned at first, despite officials evacuating her neighbourhood. Her family is convinced it's just a precaution, even as the mountain continues to rumble. Maribel decides to disobey orders and return home for items she and her sister left behind - just as the volcano finally erupts. As ash rains down, Maribel realizes she must learn to focus if she's going to survive.