The Adventures of Sherlock Holmes The Adventure of the Blue Carbuncle & The Adventure of the Speckled Band (p276-311)

In The Adventure of the Blue Carbuncle, a man named Peterson took a goose home for a Christmas dinner and his wife found a blue carbuncle (gemstone) in its throat. Holmes wanted to know how the gem ended up in the goose. So, he went to a goose dealer and asked him. The dealer told Holmes that someone was also asking about a goose and Holmes then knew that someone else knew about the carbuncle. But then a man named Ryder showed up and told Holmes what had happened. He thought that he was being followed by a thief so he fed the gem to the goose with a black bar on its tail. The only problem was that there were two geese with black bars on their tails and when he went back to retrieve the gem, it wasn't there. Holmes eventually finds out that the gem was stolen but did not threaten to put the man in jail because it was Christmas so he let him go and the man ran away.
In The Adventure of the Speckled Band, a woman named Helen Stoner went to Holmes and told him that her sister died. So, she tells him the story and Holmes also finds out that if Helen and her sister were to leave their stepfather, he would become very poor and he suspects him. Helen lives with her stepfather in an old house and weird noises happen at night. Later Helen leaves and Holmes finds a place for her to stay. By the end of the mystery Holmes finds out that Helen's father had sent a deadly Indian snake to her sisters room which had killed her. Helen's father tries to attack Helen with the snake when she found out also, but Holmes attacked it and it ran away to Helen's stepfather and kills him.