Nina always followed her older sister, Lily. But just before her thirteenth birthday, Lily died, leaving Nina behind forever.
In the three years since she lost her sister, Nina has completed Lily's secret Before Birthday lists to continue in her footsteps. But now Nina is catching up. When Nina flies to Paris, France, and completes tasks that Lily never finished, Nina finds herself magically transported inside of her own memories, face-to-face with the ghosts of her past.
With her birthday looming and the last list running out, Nina is torn between visiting her sister in her memories and adventuring in the present, including crushing hard on her art classmate, Sylvie. Should she follow Lily's instructions or try something new? And what happens when she finishes the list?