And what does the nurse (Christina Ormsay) tell us?
On the day of Mrs. Eustace Macallan's death, the nurse is dismissed from attendance, and is sent downstairs. She leaves the sick woman, recovered from her first attack of illness, and able to amuse herself with writing. The nurse remains away for half an hour, and then gets uneasy at not hearing the invalid's bell. She goes to the Morning-Room to consult Mr. Macallan, and there she hears that Mrs. Beauly is missing. Mr. Macallan doesn't know where she is, and asks Mr. Dexter if he has seen her. Mr. Dexter had not set eyes on her. At what time does the disappearance of Mrs. Beauly take place? At the very time when Christina Ormsay had left Mrs. Eustace Macallan alone in her room!
Meanwhile the bell rings at last--rings violently. The nurse goes back to the sick-room at five minutes to eleven, or thereabouts, and finds that the bad symptoms of the morning have returned in a gravely aggravated form. A second dose of poison--larger than the dose administered in the early morning--has been given during the absence of the nurse, and (observe) during the disappearance also of Mrs. Beauly. The nurse looking out into the corridor for help, encounters Mrs. Beauly herself, innocently on her way from her own room--just up, we are to suppose, at eleven in the morning!--to inquire after the sick woman.
A little later Mrs. Beauly accompanies Mr. Macallan to visit the invalid. The dying woman casts a strange look at both of them, and tells them to leave her. Mr. Macallan understands this as the fretful outbreak of a person in pain, and waits in the room to tell the nurse that the doctor is sent for. What does Mrs. Beauly do?
She runs out panic-stricken the instant Mrs. Eustace Macallan looks at her. Even Mrs. Beauly, it seems, has a conscience!
Is there nothing to justify suspicion in such circumstances as these--circumstances sworn to on the oaths of the witnesses?
To me the conclusion is plain. Mrs. Beauly's hand gave that second dose of poison. Admit this; and the inference follows that she also gave the first dose in the early morning. How could she do it? Look again at the evidence. The nurse admits that she was asleep from past two in the morning to six. She also speaks of a locked door of communication with the sickroom, the key of which had been removed, nobody knew by whom. Some person must have stolen that key. Why not Mrs. Beauly?
One word more, and all that I had in my mind at that time will be honestly revealed.