When Amelia "Mel" Eichenwald wakes up one morning, she finds herself in endless freefall towards an Earth that is no longer there, surrounded by the junk of human existence. From high heels to houses, billions of random items drop alongside her like fallout from an exploded mall. Plummet follows Mel as she attempts to survive, find allies, and negotiating the balance between becoming prey or predator. What makes us human--and what keeps us human--when gravity is all there is? How do you take a stand when there is literally no place to sit?