The story centers around the murder of Helen Stoner, who is killed by a snake that enters her room through a ventilation shaft. The snake is described as having "speckled" markings, hence the name "Speckled Band."
It's important to note that the exact species of snake is never explicitly stated in the story. However, based on its characteristics and behavior, many believe it is a swamp adder, a venomous snake native to India, where the story is set.