Monica Tsai spends most days on her computer, journaling the details of her ordinary life and coding for a program that seeks to connect strangers online. A self-proclaimed recluse, she's always struggled to make friends and counts the days until she can return home to her beloved grandparents. They are now in their 90s, and Monica worries about them constantly --- especially her grandmother, Yun, who survived two wars in China. Though Yun rarely speaks of her past, Monica is determined to find the long-lost cousin she was separated from years ago. One day, the very program Monica is helping to build connects her to a young woman, whose gift of a single pencil holds a surprising clue. Monica’s discovery of a hidden family history is exquisitely braided with Yun’s own memories as she writes of her years in Shanghai, working at the Phoenix Pencil Company.