On the anniversary of the roundup of Jews by the French police in Paris, Julia is asked to write an article on this dark episode and embarks on an investigation that leads her to long-hidden family secrets and to the ordeal of Sarah Paris, July 1942: Sarah, a ten year-old girl, is brutally arrested with her family by the French police in the Vel' d'Hiv' roundup, but not before she locks her younger brother in a cupboard in the family's apartment, thinking that she will be back within a few hours.
