Marguerite acknowledges that her heart has changed after hearing the secretary's story; though outwardly obedient to Roberval, she inwardly longs to see the secretary again. The ship is becalmed under oppressive summer heat, and Roberval grows foul-tempered, flogging drunken sailors and rebuking Jean Alfonse for his earlier estimate that they would arrive in eight weeks.

That evening Roberval orders the secretary to play his cittern. He questions Marguerite about the music, then forces her into a tense exchange about flatterers and the Psalmist's words on those with double hearts. Marguerite recognizes herself in the warning but cannot suppress her desire.

Unable to sleep, Marguerite tells Damienne she needs air. Damienne pleads with her not to go, warning explicitly about the secretary and reminding her that every man aboard belongs to Roberval. Marguerite slips away anyway, climbs to the deck, and meets the secretary by the forecastle. He embraces her; she touches him for the first time, and they part only when the watch changes.

Their meetings continue on subsequent nights. Damienne and Jean Alfonse, who shares the secretary's bunk, both notice but stay silent. The secretary tells Marguerite his name is Auguste Dupré, and they exchange stories of their pasts. He kisses her for the first time, and she confides her loneliness.

Auguste reveals that Roberval is a jealous master who would kill him if he discovered them—Roberval has told him so directly and already suspects him. When Marguerite asks how he can risk it, Auguste replies that Roberval has risked their lives already with the voyage itself. Frightened but unwilling to stop, Marguerite agrees to keep meeting him.