Lina is described as having long, dark hair, and being of average height with a slender build.
On her first day she receives a strange message from Looper to the mayor, talking about a "delivery". When she goes to the Gathering Hall, similar to a city hall, to deliver the message, she is told to wait, and so, gets bored and decides to explore. She goes up to the hall's roof and waves at the people below in Harken Square, before she is caught by the guard Redge Stembark. The mayor finally arrives, and she delivers the message.
Two weeks later, when Lina returns home from work, she finds the house in a mess, with her grandmother ripping stuffing out of the cushions on the couch. When Lina questions her actions, her grandmother replies that something important is lost and is looking for it, although she does not remember what it is. She then asks where Poppy is, and Granny Mayfleet ponders for a while before remembering she is down in the yarn shop. Lina fetches Poppy and upon returning to her home, finds Granny Mayfleet putting the stuffing back in the couch. Granny tells Lina sadly that it was "not in there", and that it was lost a long time ago. She also tells Lina they heard her grandfather, the seventh mayor, talking about "it" and saying he couldn't get at it and that it was lost before he died, but he didn't say what it was. Lina initally dismisses it as nothing important and asks their neighbor, Mrs. Murdo to check in on things.
She goes to deliver a message to Clary Lane, a friend and worker at the greenhouses. On her way out, Lina hears crying and sees Sadge Merrall, a Supply Depot Clerk, stumbling around nearby. Clary goes to help him, and Lina, though told to leave by Clary, stops to listen. She learns he tried to journey into the Unknown Regions, and without light was forced to return.
A few days later, Lina goes out to Looper's shop to buy pencils, which she uses to create drawings of her imaginary city, very much unlike Ember. She brings Poppy with her. The prices are extremely high but Lina finally buys two pencils. When Lina turns around, Poppy is missing and she rushes out into the streets to look for her, just before the lights flicker out. When they return, Doon approaches carrying Poppy.
Because of the recent power failures, a town meeting is called by the mayor. At Harken Square a crowd gathers, He tells them there are "slight difficulties" but they will pass and he is "making every effort" and that "solutions are being found." This prompts anger in the crowd as they demand "what solutions?"
When Lina arrives at the apartment later that day, she finds Granny looking through the closet and Poppy behind the couch. When Lina goes to investigate, she sees a small, shiny box on the floor next to Poppy. She also sees Poppy is chewing on paper with small, printed words on it that interest Lina because it does not look like handwriting, but the print made with machines from the days of the The Builders. After putting Poppy and Granny to bed, she sits down to try and read the message; however, Poppy had already chewed it beyond repair.
Lina begins by attempting to put the pieces back together. At first, none of the scrambled words make sense until she comes across the word 'Pipeworks'. Seeing another word, 'door', Lina begins to suspect that the message may lead her to something that can save the city. She ultimately decides to go see Doon the next day to show him.
Upon bringing Doon back to the apartment and showing him the message, he recounts to her the memory of a door he found while exploring the Pipeworks. Believing that to be the door in the message, the two sneak into the Pipeworks and make their way to it, only to find it locked like before. Before they leave, however, they catch a glimpse of a man who goes down the tunnel himself and opens the door before leaving soon afterward.
A few days after this discovery, Granny dies from a sickness, and Lina and Poppy move with Mrs. Murdo. Lina is now more determined than ever to decipher the instructions and learns from Doon that the room they had found in the Pipeworks is not an exit from Ember; it is actually used as a storage space that the Mayor uses to house a massive amount of food and supplies that he steals from the storerooms, with the help of drugs, which Lina remembers using earlier. The two report his crimes to the guards, and Doon, masked by their success becomes reluctant to see any importance tied to the message in the box.
Frustrated, Lina heads to the greenhouses to request help from Clary, and upon showing her the instructions, Clary notices a word at the top, 'Egres', which Lina assumed was 'Egreston' and probably the name of a past mayor. However, Clary tells her that by adding an 's' to the word, it becomes 'Egress', which means 'exit'. This confirms Lina's suspicion that the message is indeed instructions on exiting the city.
Lina is very ambitious in the first book of the series, The City of Ember, but just like every other teenage girl, she has her mood swings at times. She is excited as her and Doon are finding the way out of Ember. She is sad when Granny dies. She is very curious; her curiosity leads to much more trouble. She is brave and determined. Lina is willing to take a risk, and cares deeply for Poppy and Doon.