The hobbyist deals with a murderer who went to a druggist to have an undetectable poison for his murder, because he heard a rumour about this druggist.
The druggist said Mr Sangstrom (the murderer) to tell him the way of the murder. When Mr Sangstrom talk about the story and he said that he would kill his wife, the druggist prepared two coffee to invite him. When Mr Sangstrom had quite finished, he asked the druggist to give him the poison, but the druggist had already put the poison in Mr Sangstrom’s coffee. Mr Sangstrom pulled a pistol from his pocket, but the druggist wasn’t worried because he had the antidote. Mr Sangstrom said to give him the antidote, but the druggist obliged Mr Sangstrom to write a confession of his intention to murder his wife and after, the druggist had been going to send it to a friend.
And he obliged Mr Sangstrom to give him 1000 dollars for the antidote. His hobby was preventing murders.