"The Adventure of the Speckled Band" follows Helen Stoner seeking Holmes' help regarding her sister's suspicious death. Their stepfather, Dr. Grimesby Roylott, exhibits aggressive behavior and controls the family estate. Before her death, Helen's sister, Julia, mentioned a "speckled band."Holmes investigates and discovers Roylott's sinister plot to kill Helen, using a poisonous snake, a speckled adder, through a vent. Holmes intervenes, preventing Helen's murder by altering the snake's path, causing it to turn on Roylott, leading to his demise.Holmes uncovers the truth, saving Helen and exposing Roylott's murderous intentions. This story showcases Holmes' deductive prowess in solving a perilous case and protecting the innocent.