"Escape from Liberty Gardens" is the sixth and final chapter in the Left Behind DLC of The Last of Us. It depicts Ellie and Riley's escape from several Infected, and how Ellie received the bite that led to her immunity.
Ellie and Riley manage to get out of the music store and barricade the door with a heavy crate, leaving their backpacks behind. Riley opens the door but is met with more Runners. Riley comes through, shooting a Runner dead.
Riley shoots the lock off another door, forcing her way through. The two sprint to and over a truck. Riley stops to let Ellie catch up but pushes on as the Infected close in. Ellie crawls under some rubble, but is grabbed by a Runner. Desperate, she frantically kicks it to death. She catches up to Riley, who is struck by a Runner herself. Ellie jumps on to the Infected and furiously stabs several times with her switchblade. Riley is shocked at Ellie's brutal attack, but carries on up a flight of stairs.
The pair realize the scaffolding near the roof is their only way out. They reach the top, but more Runners block their path, forcing them to divert from the hall to a room but are blocked again, vaulting onto the scaffolding below. Riley succeeds in making the jump, but Ellie struggles.
They finally make it to an open window, climbing up as fast as they can. Riley reaches out to Ellie, but the ledge gives way, with Ellie falling down below. Dazed, she is unable to prevent a Runner from tackling her to the floor and screams for Riley's help. Riley shoots two Runners and helps Ellie up, but is tackled by another Runner. Ellie falls on top of it as she forces her switchblade into the Runner's throat, splitting it open.
Ellie is relieved that the Infected are dead. Riley, however, is not as joyful, looking at Ellie's arm. Ellie looks down, noticing her bite wound. Ellie is shocked, wiping the blood from it only to find the wound still remains. Riley reveals that her hand is bitten as well. The two are Infected.
Overcome with anger, Ellie smashes several plant pots with a pipe before tossing it away, crying as she does so. Riley gives them their options: committing suicide, or fighting off the infection for as long as they can. Riley doesn't want to give up on living, but Ellie wants a third option; her friend admits there isn't one. Riley gets up, saying they should leave before more Infected show up, as Ellie wipes the tears from her face.
In the present day, Ellie successfully stitches up Joel's wound, admitting she had practice when she stitched up her bitten arm. Once done, she straps Joel to a sled, wraps him in several blankets, and leaves the Plaza on Callus.