In a memory from when Frankie and George are ten, Frankie describes a make-believe wedding they hold under the apple tree in her backyard. Using a curtain as a dress, George's grandfather's hat, flowers from the Big House garden, and vows written on scraps of paper, they solemnly declare themselves married with a handshake and rice. The scene frames the depth and innocence of their bond.

Frankie then explains why she was often angry at that age. Her mother had recently returned after an eighteen-month absence on the East Coast, where she had worked with researchers studying and rescuing endangered North Atlantic right whales. Before leaving, Frankie's mother had filled Frankie's childhood with whale facts, maps, stories, and even named Frankie after a real whale, Francesca, but when she vanished without warning, Frankie felt abandoned and betrayed.

After her mother comes home, George quickly becomes attached to her. Because George lost his own mother at seven, he is drawn to her warmth, attention, and food, while Frankie's mother openly praises and fusses over him. Frankie tries to tolerate it, but when her mother starts talking enthusiastically about whales again over apple-berry crisp and George says he wants to work with whales too, Frankie's jealousy and hurt boil over. Frankie storms off, tells her mother she wishes she had never come back, and later tells George she hates him and never wants to speak to him again.

The next day, George responds with a letter instead of fighting back. He admits that he likes Frankie's mother and sometimes wishes she were his, but insists that he likes Frankie more than anyone and promises to prove he will be her best friend forever. Frankie meets George in their secret cupboard in the Big House library, where George has gathered everything needed for a wedding, and the two perform the ceremony. The pretend marriage becomes George's way of repairing the rupture and promising lasting loyalty.