The Butler, Agreeing is Chapter 185 of the Kuroshitsuji manga.
Summary[]
From outside the room, Ronald listens to Baldroy and Ada's conversation while thumbing through his journal and checking the time.
Inside, Ada tells Baldroy that, after she returned from Sudan, she was relieved of her duties and went to work as a nurse in a suburban sanatorium. She wanted to enforce Florence Nightingale's nursing practices in the messily-kept sanatorium, but the doctors and the other nurses did not want to hear anything about it. To them, she was only a nuisance. She frequently moved sanatoriums, but it was always the same; no one wanted to hear what she had to say.
Ada eventually ended up at Karnstein Hospital where she was approached by a doctor who belonged to the Aurora Society. He offered her an opportunity to realize a healthier way of nursing, and she jumped at it. The only condition the Aurora Society had for building the Athena Sanatorium was that Ada had to collect blood from her patients because they wanted to use it for "medical research." Although she had her doubts, Ada accepted the condition because she was simply so happy that her dream was finally about to come true. Even after she read about the Sphere Music Hall's fall in the newspapers and realized that the music hall and the sanatorium were connected, Ada chose to ignore her employers' evildoings as she did not want to lose the sanatorium.
A while ago, the Aurora Society's demand for blood increased. Ada protested against this as drawing more blood would jeopardize the lives of her patients, but they held firm; she either delivered the amount they wanted or they would stop funding the sanatorium. This has thrown Ada into a crisis. She does not want to harm her patients, but she also cannot help them without funds.
Baldroy tells her that he was given only one command: To dismantle the operation if he finds any evidence of blood collection. He would kill her and drive out the patients—if the blood collection keeps on going. If Ada stops it though, he will be her ally. He could see that there is nothing wrong with her dream, and if she promises never to betray her principles again and turn her back to the Aurora Society, he will support it. Ada promises this. Then, Baldroy asks when the next blood collection will be. When she says that it will be tomorrow, Baldroy hurries out of the room. He has to plan something on his own as there is no time to contact Ciel.
Running downstairs, Baldroy is stopped by Lau throwing needles at him. Lau holds a needle against Baldroy's face and tells him that he is very disappointed by his answer.