Mr. Robert Ferguson turns to Sherlock Holm for help. A few years ago he married a young beautiful Peruvian, but after a while his love for her began to cool down, although his wife still loves him. From his first marriage, he has a fifteen-year-old son, Jack, who injured his spine and became a cripple. He and his wife dislike each other – his wife throws himself at him without the slightest excuse. One time she hit so hard that she left a scar. But it’s even more terrible for their common child.
Somehow the nurse left the baby alone for a few minutes, and when she came back, she saw how her mother dug her teeth into the baby’s neck, so that blood flowed from the wound. The nurse wanted to call for help, but the woman asked not to tell anyone and even paid for the
Unable to withstand, the nurse admitted in all Ferguson, who decided that this was the result of her inflamed imagination, but then a child’s cry came. They rushed into the room and saw that there was blood on the bed sheet of the child, and lips that were bleeding from the mother’s bed were bloodied. Mr. Ferguson locked up the refusal to give any explanation to his wife, considering her a vampire, and he himself asked the great detective to come to his estate and understand the situation.
Arriving at Mr. Ferguson’s house in Sussex, Holmes sees collections of South American utensils and weapons. He also draws attention to the spaniel, which four months ago fell ill with meningitis. Holmes comes into the room to Mrs. Ferguson. A woman – a nervous breakdown due to the inability to see the child. After acquainting himself with the children of Mr. Ferguson and his servants, Holmes writes a sick note asking to meet.
Dr. Watson, Holmes and Mr. Ferguson come to her room. Holmes removes all suspicions from a woman, considering the stupidity of accusations of vampirism. The woman was afraid for the child and sucked poison from the wound. Truth she was afraid to open, since the culprit was Jack, who hates his stepmother and is jealous of his father for his new wife and young son. Before kicking a baby with a poison needle that he took from a collection of weapons, Jack tried the poison on a spaniel.
The great detective advises Mr. Ferguson to send Jack on a journey, and gives his husband and his wife the opportunity to find out their relationship.