Arcane begins against the backdrop of the stark contrast between Piltover (the City of Progress) and Zaun (the Undercity).

Two sisters, Vi and Jinx, live in Zaun with their adoptive father, Vander.

Living in poverty, Vi and her friends occasionally raid Piltover to make ends meet.

One day, a major accident occurs while they are robbing a scientist's home in Piltover, causing tensions between the two cities to escalate to an extreme level.

As Piltover's crackdowns intensify, the dissatisfaction of Zaun's residents grows.

The ambitious Silco emerges, sparking a power struggle within Zaun, while Hextech—a new technology combining magic and science—is introduced for the first time.