Therefore it must have been Mrs. Cavendish who entered the deceased's room through the door communicating with Mademoiselle Cynthia's room."
The door between these rooms has only a simple lock.
mnli hypothesis: The door between these rooms has only a simple lock. premise: Therefore it must have been Mrs. Cavendish who entered the deceased's room through the door communicating with Mademoiselle Cynthia's room."