What is the plot of Between Shades of Gray?

"Between Shades of Gray" by Ruta Sepetys, published in 2011, is a fictional story based on real-life testimonies of people's experiences during the Stalinist repression of the mid-twentieth century. It tells the story of its narrator, Lina Vilkas, following her journey of being deported from Lithuania and ending up in a labor camp in Siberia.
Lina lives with her family in Lithuania, but her family is suddenly broken up when the NKVD (Soviet officers) enter their home in the middle of the night: "They took me in my nightgown" she begins. Lina, her mother, Elena, and brother, Jonas, are put on a train to a work camp in Siberia. Her father is separated from them.
From the beginning, we know she will survive the ordeal as she states early on that "it was the last time I would look into a real mirror for more than a decade." Tension is introduced with the reader knowing that she will be living through an ordeal but without knowing what that will involve.
When they arrive at the labor camp, Lina, her mother, and her brother end up living with Ulyushka. They have to work hard for their food and survival, digging beets alongside other Lithuanian deportees.
The story continues by detailing their life in the camp and the various relationships they form with other deportees, such as Andrius Arvydas, and the Soviet officers, in particular Nikolai Kretzsky, who struggles with doing an immoral job and is somewhat kind to Lina and her family. Lina documents their life experiences in her artwork. Andrius and Lina become friendly, but Lina and her mother are moved to another work camp.
Lina does survive the ordeal, but her mother does not. Lina thinks she is close to not managing to survive but in the end is saved with the help of a doctor who turns up at the camp.