There are really three questions here. Firstly, the narrator of the story is Dr Watson. He admires the great detective, Sherlock Holmes, whose adventures he chronicles and who solves the mystery of the speckled band.
Secondly we note that the two men are very different, which makes Watson the perfect foil to Holmes. Watson comments at the beginning of the story that Holmes indulges in his detective work for personal satisfaction rather than material gain: explaining that as he worked-
for the love of his art than for the acquirement of wealth, he refused to associate himself with any investigation which did not tend towards the unusual, and even the fantastic.
Watson is more of a creature of habit and routine – as he notes about the unusual early rising of Holmes which disturbs Watson on the day the case comes to light
I was myself regular in my habits.
Watson has a more stable occupation as a doctor but is always on hand to indulge in the exciting exploits of Holmes’ detective work. He has a great respect and fascination with the skill of his friend-
I had no keener pleasure than in following Holmes in his professional investigations, and in admiring the rapid deductions, as swift as intuitions, and yet always founded on a logical basis with which he unravelled the problems which were submitted to him.
The mystery unravels in Stoke Moran, on the border with Surrey in England. Holmes visits the dwindling estate of Dr Grimesby Roylott and establishes that he has plotted to kill his second stepdaughter, having succeeded with the first, by establishing elaborate modifications to her room to facilitate a fatal attack by a swamp adder.