How does Arthur Conan Doyle meet the readers' expectations of a detective story when he writes "The Adventure of a Speckled Band"?
The reader expects to see the detective use both the obvious and obscure clues to solve the crime. A clever detective will see through the red herring, to the truth of the case. Also, the reader appreciates a punishment which fits the crime.
Holmes is able to investigate the financial affairs of Dr Roylott to see that he will be seriously compromise should his stepdaughters marry. Roylott’s temper and violent past show that he is capable of cruelty, and Holmes observes the marks of violence upon Miss Stoner:
Holmes pushed back the frill of black lace which fringed the hand that lay upon our visitor's knee. Five little livid spots, the marks of four fingers and a thumb, were printed upon the white wrist.
Holmes is able to dismiss the red herring of the gypsies as being the ‘band’ referred to by young woman as she dies. He does see that the animals on the property are significant, as are the saucer of milk near the safe, the false bell-pull and the fixed bed.
The reader is satisfied that Roylott’s cruel and unusual plot serves to punish him in the end. It is a natural rather than a legal justice, and it completes the story well. Holmes is aware of his part in the death of Dr Roylott, but feels his actions are justified-
In this way I am no doubt indirectly responsible for Dr. Grimesby Roylott's death, and I cannot say that it is likely to weigh very heavily upon my conscience.