Earth has survived catastrophic solar winds under the protection of the Grid, its planetary defense shield. Kim Sae Ha, an employee of the Bureau, encounters a murderer. Jung Sae Byeok, a detective, is dispatched to arrest the murderer. While in pursuit of the fugitive, she witnesses an unbelievable phenomenon: the founder of the Grid - a ghost of the past - has reappeared after 24 years. But why is she abetting the fugitive? This is a thriller that pursues the mysterious truth behind what saved humanity from an apocalypse.