In late June in Carriveau, Vianne battles stifling heat and growing fear as Sophie’s illness worsens into a frightening, unbreakable fever with violent coughing. Realizing she misjudged her daughter’s earlier complaints, Vianne tries to cool Sophie with water and coax her to drink, but Sophie cannot keep anything down and begins thrashing and screaming.

When Vianne admits there is no medicine to be found in town, Beck appears and reveals he has heard Sophie coughing all night. Beck produces a small bottle of antibiotics and insists Vianne take it. Vianne accepts, understanding it is a serious favor with an unspoken cost, and a charged, mutual awareness passes between them as Sophie lies dangerously still.

In July, Isabelle arrives at the British consulate in San Sebastián after another difficult Pyrenees crossing. Ian (code name Tuesday) pays her and warns that the Germans are hunting the Nightingale and trying to infiltrate the escape route by posing as downed airmen. Isabelle refuses to slow down, then sends Paul a coded message and returns to Paris by a circuitous route, paying safe-house helpers along the way and privately missing Vianne and Sophie but refusing to risk visiting them.

Back in Paris, Anouk warns Isabelle of secret Sunday-night “clerical work” recruited by the Germans, and Isabelle reports to the prefecture of police. Inside, she finds hundreds of women sorting index cards listing Jewish families, instructed to separate foreign-born Jews from French-born Jews. Isabelle grasps the scale of what is happening, panics upon finding a card for Paul Lévy, hides it up her sleeve, and escapes the building by pretending to be ill when a policeman confronts her.

Isabelle brings the information to her father at his apartment: the French police and Vichy authorities are collecting names and addresses of foreign-born Jews. As buses roll silently down the avenue, a warning pamphlet arrives stating the police will round up foreign-born Jews for deportation to camps in Germany. Isabelle and her father act immediately, hiding Ruth Friedman and her daughters in their secret room, but Isabelle is too late to reach the Vizniaks; she watches French policemen force Lily Vizniak and her children to pack and leave, rejecting Isabelle’s offer to take the children because she still trusts the authorities.