What do holmes and watson discover about Stapleton's identity?

Holmes and Watson discover that Stapleton is not only posing as a naturalist but is also a member of the Baskerville family, being a descendant of the line. He has been using his knowledge of the moor and the legend of the Hound to scare Sir Henry Baskerville and eliminate him as a rival for the Baskerville inheritance. This revelation reveals Stapleton's true motives and his connection to the family curse that has haunted the Baskervilles for generations.