Back in a Flash is the first chapter of The Last of Us DLC, Left Behind. It introduces the player to the character Riley Abel and establishes a missing link of what happened to Ellie and Joel before their encounter with David.
The scene cuts to Ellie, back in the summer. Her friend, Riley, comes in and pretends to be an Infected, playfully biting her neck. Ellie throws her off and threatens her with her switchblade. Realizing it is Riley, she asks why she's here. Riley reveals she is a Firefly, prompting Ellie to check for guards. The pair discuss when they last saw each other and Riley convinces Ellie to come with her exploring, despite Ellie remarking she has military drills. Ellie confesses it is stupid to run off like this, but Riley comforts her, taking her pendant back, stating they haven't got in to trouble yet.
The scene cuts back to the present day, where Ellie is desperately trying to find anything to help a mortally wounded Joel with. She finds some binding and proceeds to tape scraps of her summer shirt over Joel's wound. She informs him she has to find something more to sew him up with. Asking Callus to look after him, she departs the store.
Back in a FlashEdit
She comes to a pharmacy and looks around, finding that everything has been either used or taken. She notices one door is locked. She looks through the glass window and sees a first aid kit on the ground. Wanting to take it, she searches for a key. She comes across a note that tells her the combination to the American Princess store next door and that the pharmacist was locked in their after attacking someone.
She goes to the store, opening the lock. The place is filled with spores but Ellie's immunity protects her. She reaches the back of the store finding a decaying corpse. She searches it, finding the key to the pharmacy along with a a picture of a man and a woman.
As she goes to exit, a Clicker passes by the store. She quickly stabs it in the head with her switchblade, taking a bottle of alcohol it dropped.
Reaching the HelicopterEdit
She returns to the pharmacy, opening the door. She opens the medical case, only to find it is empty. Frustrated, she kicks the case away. She notices a Blackhawk helicopter has crashed through the roof outside the pharmacy. Hoping to find something there, she heads towards it.
Ellie exits the salon and descends some stairs. Unable to go any further, she vaults the railings, declaring "Here we go".