The narrator and her mother had gone to London to bring the narrator to the dentist. After that, they decided to go to a café. When they went out, an old man with a silk umbrella came up to them. He asked her mother if he could sell his umbrella for a low price to pay the taxi because he had just lost his wallet and his oldness prevented him from go back home by walking. But her mother didn't trust him at all but at the end, as she satisfied herself he wasn't a trickster, she accepted the old man proposition.
But a few seconds later, the narrator saw the old man walking fast. The mother was furious because this man trapped her: he pretended he had weak legs to get money from her. So, she began to follow him and she arrived at a pub where the old man had just entered. He was drinking a whisky and he paid it with the money he got from her. Then, the man stood up, walked towards the exit and before he went out, he took an umbrella. The two girls continued following him and they saw the man selling the umbrella he had just stolen to a man. But this time, he didn't go towards the pub but in the opposite direction: he didn't do that little trick twice in the same pub. It was the perfect stratagem.