Upon returning to the human world, Sunset Shimmer finds Canterlot City twisted into a biomechanical hellscape, with all living things transformed into grotesque mockeries of their former selves. Led by the human Starlight Glimmer, the forces of Phyrexia loom omnipresent over all aspects of life.

Joining her six closest friends, Sunset is now faced with a seemingly impossible task. Can the magic of friendship find a cure for phyresis, or will the world be forever doomed to compleation?