This is an automatically translated description

The story is from the author's list of 12 Favourite Sherlock Holmes Stories. Holmes and Watson go on holiday to Cornwall. A few days later, they are visited by Mr Mortimer Tregenis and Mr Ryndhay, who report that two of Mr Tregenis's brothers have gone mad and his sister has died.
Brenda died with a horrified expression on her face.
After a while, Mr Mortimer Tregenis himself died, and so did his sister. Holmes explores the room and picks up a lamp that was on the table in the deceased's room. When it was lit, the killing effect was immediate, and Watson pulled Holmes out of the room in time.

Holmes realises that Mortimer Tregenis used a poisonous powder to kill his brothers and sister, but who killed him? Melania
Duration: 01:05:55