Knowing her weakness in hand-to-hand combat against both enemy groups, Ellie uses her ingenuity to start a fight between the cannibals and the infected, only eliminating or avoiding the remnants afterwards. However, she is impeded by both the infected as well as survivors from David's group. Shifting back to the Colorado Mountain Plaza, Ellie attempts to make her way back to Joel with the medical kit. Riley starts to say something about how Marlene won't approve, but she is interrupted by runners that were attracted by the music. Riley drops her pendant in response and Ellie kisses her. Ellie pleaded with Riley not to go despite having earlier encouraged her to. To cheer themselves up, the girls had a water gun fight and danced to some music. Riley evades the question until reluctantly revealing that the Fireflies assigned her to another group in a different city, and she wanted to see Ellie one last time despite Marlene forbidding her to do so.

However, Ellie keeps asking why Riley brought her here. The two girls played around, involving masks, brick throwing and a carousel. Revealing that she became a Firefly during her absence, Riley takes Ellie to the abandoned shopping mall she brought her to when they first met. Set three weeks before the The Last of Us takes place, Riley surprises Ellie at the boarding school. Avoiding the infected she makes her way to the helicopter, learning the fate of its survivors along the way and finally finding a medical kit. However, she spots a downed military helicopter.

She first comes across Weston's Pharmacy, which has already been picked clean of all medical supplies. During the main events of The Last of Us, the scene begins with Ellie hiding Joel in an abandoned Colorado Mountain Plaza, using her summer shirt and some binding to stem the bleeding from Joel's impalement while she explores the mall for medical supplies. The story of Left Behind follows a non-linear timeline of both Ellie's time with Riley before meeting Joel, and the aftermath of the fight with David's group at the University of Eastern Colorado.

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