The adventure of the speckled band.
"The coroner investigated my sister's death with great care, because no-one in the area trusted doctor Roylott. But the coroner was not able to find out what killed her.
I gave evidence to the court that the door of my sister's room had been locked on the inside. The windows were blocked by shutters with iron bars, and these were locked in the night. The police checked the walls carefully but they were completely solid all round, and the floor was also thoroughly examined, with the same result.