Mr. Tulkinghorn is getting some fresh air in a balcony of sorts of his turreted room in Chesney Wold when he is interrupted by Lady Dedlock. She is angry. She wants to know if it was necessary to have told her story (though it was told with the protagonist's true identity concealed) to so many people. Mr. Tulkinghorn replies that it was necessary to have Lady Dedlock know that Mr. Tulkinghorn was privy to her secret past. Lady Dedlock asks whether Rosa's associates (Mr. Rouncewell and his friends) are also in the know of Lady Dedlock's secret past as Mr. Tulkinghorn suggested that they were in his story. Mr. Tulkinghorn answers 'no,' admitting he had speculated as much on the likelihood that that may actually be the case.
Subsequently, Lady Dedlock admits that if Mr. Rouncewell knew who Lady Dedlock was in relation to his dead friend Captain Hawdon, then that Rosa would be the recipient of much harm. For Rosa's sake, Lady Dedlock urges Mr. Tulkinghorn to be judicious when speaking of Lady Dedlock's secret past. Then Lady Dedlock asks Mr. Tulkinghorn whether there are any legal documents that she could sign that would protect her husband Sir Leicester from the fallout that would invariably result with the disclosure of Lady Dedlock's secret past. Mr. Tulkinghorn replies that no such measures are necessary.
Presently, Lady Dedlock exhorts Mr. Tulkinghorn to do all that he can to protect his client Sir Leicester as she will leave Chesney Wold this instant never to return. Mr. Tulkinghorn objects and pleads Lady Dedlock to hear out what he has to say. Reluctantly, Lady Dedlock obliges Mr. Tulkinghorn. Mr. Tulkinghorn explains that his only duty is to Sir Leicester, and considering the reliance Sir Leicester has invested in Lady Dedlock, it is incumbent on Lady Dedlock to stay lest her disappearance plunge Sir Leicester into a state of irrevocable despondency. Reluctantly, Lady Dedlock agrees to Mr. Tulkinghorn's plan: To continue maintaining the deception until such time it's necessary to reveal the truth.