A team of treasure hunters take over Alcatraz Island in search of diamonds and encounter a shape-changing alien.

Ryan Kristoff, once a decorated naval captain must fight his past and inner demons to save his family from the "dormant" Mount Diablo. His estranged wife, a distinguished geologist, realizes that the fabled Diablo is about to erupt. She embarks on a mission to convince the local authorities to evacuate the city.