The flashback is set in the Boston Quarantine Zone (QZ) several months before Ellie meets Joel.
The episode is a faithful retelling of the Left Behind DLC from the original video game. The Last of Us: 1Г—7
Riley shows Ellie what she calls the "wonders of the mall": The Escalator: Ellie's first time seeing "electric stairs". The flashback is set in the Boston Quarantine