When the moon is low / a novel by Nadia Hashimi.

Enhanced descriptions from Syndetics:

Mahmoud's passion for his wife Fereiba, a schoolteacher, is greater than any love she's ever known. But their happy, middle-class world--a life of education, work, and comfort--implodes when their country is engulfed in war, and the Taliban rises to power.

Mahmoud, a civil engineer, becomes a target of the new fundamentalist regime and is murdered. Forced to flee Kabul with her three children, Fereiba has one hope to survive: she must find a way to cross Europe and reach her sister's family in England. With forged papers and help from kind strangers they meet along the way, Fereiba make a dangerous crossing into Iran under cover of darkness. Exhausted and brokenhearted but undefeated, Fereiba manages to smuggle them as far as Greece. But in a busy market square, their fate takes a frightening turn when her teenage son, Saleem, becomes separated from the rest of the family.

Faced with an impossible choice, Fereiba pushes on with her daughter and baby, while Saleem falls into the shadowy underground network of undocumented Afghans who haunt the streets of Europe's capitals. Across the continent Fereiba and Saleem struggle to reunite, and ultimately find a place where they can begin to reconstruct their lives.