As [Holmes] spoke he drew the dog-whip swiftly from the dead man’s lap, and throwing the noose round the reptile’s neck he drew it from its horrid perch and, carrying it at arm’s length, threw it into the iron safe, which he closed upon it.
The Rising Action
The rising action comes when Holmes and Watson begin investigating the strange and alarming story Miss Stoner tells about her present concerns and and about the death of her newly engaged twin sister two years earlier. Her present situation bears so much resemblance to her late sister's situation, including metallic and whistling sounds and sudden abrupt building repair projects, that she turns for help to Holmes. The first step in the rising action is the threatening visit of her stepfather, Dr. Grimesby Roylott of Stoke Moran. He stands darkly in the doorway, an imposing figure, and demands in a loud voice that Holmes refrain from any interference with his family affairs. To prove his point that he is a dangerous man, he invades the room and bends a fire poker with his bare hands.
Falling Action
The falling action comes after the adventure draws to a climactic close having been safely concluded, with nefarious plans thwarted, threatened people saved and the guilty disposed of (in one way or another). In this case, Holmes, sitting in a deeply dark room, listening intently, has climactically stopped the speckled band snake ("Indian swamp adder") from progressing on its murderous mission and has beaten it, turning it back upon Roylott--who had sent it through the vent from the adjoining room--where it attacks and kills Roylott.
The falling action begins when Watson gasps, "What can it mean?" and Holmes replies, "It means that it is all over." The falling action continues for a short space, while Holmes says the ending may "be for the best" and asks Watson to take his "pistol" in hand as they "enter Dr. Roylott’s room." They go down the hall, knock fruitlessly at the door, enter and are met with the chilling site of Roylott's still body, with the speckled band snake round his head.