The morning after discovering Robert's affair with Peter Ong, Lesley wakes with a sense of clarity. She retrieves a Nyonya kebaya she had made years ago—an outfit Robert once mocked—and dresses in it to attend Arthur's tea party for Sun Yat Sen. Her amah Ah Peng tells her that only she herself can cause her sorrow, and gives her a donation envelope from the household staff.

At Arthur's Leith Street home, Lesley is the only European among the wealthy Straits Chinese guests. She makes a large pledge in Robert's name, meets her brother Geoff, and confides Robert's affair with a Chinese man. Geoff urges divorce, but Lesley refuses for her sons' sake. Sun Wen delivers a stirring speech, then privately asks Lesley to help enrol his daughters at Convent Light Street, fearing for his life as he plans to topple the Qing government.

Alone with Arthur afterward, Lesley invokes "the House of Doors." They take separate rickshaws to the Armenian Street shophouse, where during a violent thunderstorm they begin a passionate affair. Lesley keeps the key. On her way home she stops at a photographer's studio and has her portrait taken in the kebaya. She greets Robert calmly when he returns from KL, feeling irradiated and acutely aware that she is now an adulteress.

The affair becomes Lesley's sanctuary. Twice weekly she slips from the reading club to the House of Doors, insisting on absolute secrecy—no letters, no public meetings. Arthur shares his grandmother's history (a Taiping conscript turned Penang printer), plays Reynaldo Hahn on the guzheng, serves rare tea, and tells her the casuarina is called the "whispering tree." When Arthur lingers outside Cassowary House, Lesley angrily insists their worlds remain separate. She admits Robert stopped sleeping with her years ago but refuses to reveal who his lover is.

At a party, Ethel's lawyer Wagner ambushes Lesley, asking her to testify at Ethel's trial as a character witness, since every other woman has refused. Lesley confides to Arthur that Ethel had been sleeping with Steward since December and shot him when he tried to force her after she ended it—truths Ethel will not allow her lawyer to use. Arthur urges Lesley not to go to KL, but she knows Robert would find her absence suspicious.