Julia Stoner's death is baffling in its circumstance, but the recount of the tragic event provided by her sister Helen is extremely useful to Holmes in establishing the motive and means for the strange events at Stoke Moran.
Helen explains that her sister's room was next to that of Dr Roylott. Julia went to her room after her stepfather, but was troubled by his cigar smoke so went to talk to her sister. In the course of the discussion she revealed that she had been disturbed for the previous three nights by a whistling sound. Helen had not heard it. Julia returned to her room and both ladies locked their doors: Dr Roylott has several wild animals on the property that they did not wish to encounter.
During the night Helen woke to the sound of her sister's screams. She also heard a whistle, and a metallic clang. As Julia's door opened, Helen saw her sister writhing in pain and gesticulating towards Dr Roylott's room, proclaiming -
'Oh, my God! Helen! It was the band! The speckled band!’