The story follows Seo-yeon (Park Shin-hye), a young woman who returns to her childhood home in 2019. After losing her cellphone, she plugs in an old cordless phone and begins receiving calls from a woman named Young-sook (Jeon Jong-seo).

Between 2019-2021, several telecom employees were caught selling call indexes on the darknet. These datasets, labeled call_index_2020_full.txt , have been used for blackmail and corporate espionage.

The index remained stable except for a temporary dip in April (index dropped to 79.1) due to unexpected volume spikes, but recovered by June through workforce reallocation.

The dominant entry. The call was not a gentle ring but a klaxon. Under this heading, we file the daily press briefings, the exponential curve flattened on whiteboards, and the silent scream of supply chains snapping. To answer this call meant abandoning the long-term for the next twelve hours.

In a small, cluttered office in a nondescript building, a young woman named Maya sat staring at her computer screen. She was a data analyst, tasked with creating an index of the best-performing companies in the world for the year 2020.