The young man who sits beside Norman Gortsby is acting angry for Gortsby's benefit.
"You don't seem in a very good temper," said Gortsby, judging that he was expected to take due notice of the demonstration.
The young man turned to him with a look of disarming frankness which put him instantly on his guard.
"You wouldn't be in a good temper if you were in the fix I'm in," he said. "I've done the silliest thing I've ever done in my life."
Then this stranger tells Gortsby a complicated and ingenious story about the silliest thing he ever did in his life. He just arrived in London from the country intending to stay at the presumably prestigious Patagonian Hotel in Berkshire Square and found that the building had been torn down. So he had to take a taxi to a hotel he knew nothing about. From that hotel he sent a letter to his "people," presumably his parents, giving them the name of the new hotel, since they were expecting to be able to reach him at the Patagonian. This young con man claims he is so fastidious that he can't use hotel soap and had to go out to buy a cake of soap from a chemist's shop. "Hotel soap" must have been similar to the kind of soap we get in hotels and motels today--just little hard, slippery pieces wrapped in paper. So when the young man went out to buy a cake of quality soap he left most of his money in his room. And then after getting the soap in one place and stopping for a drink at another place, he couldn't find his hotel.
The story cleverly suggests that the young con man is something of an aristocrat who lives in a country estate and is used to having the best of everything. This is a different approach than that used by most panhandlers and grifters. By pretending he doesn't really need money except for an emergency loan, the con man expects to get substantially more from a potential victim like Gortsby because the victim would expect to get his money back within one or two days. The con man supposedly only needs enough money to stay in another hotel overnight, where he can write his "people" and get, not money, but the address of the hotel where he registered after he could not stay at the Patagonian. He tells Gortsby pointedly:
"There's a nice predicament for a fellow who hasn't any friends or connections in London!"
This is intended to give Gortsby the impression that he could make a friend with a young man who is presentinig himself as a member of a better social class than Gortsby, who is probably an office clerk resting on a park bench after a day's work. Gortsby is skeptical from the beginning. He has heard too many hard-luck stories. Saki describes him as being "instantly on his guard" and as responding "dispassionately" to the stranger's statement that he had "done the silliest thing I've ever done in my life." But when Gortsby happens to find the cake of soap by the bench, he experiences several different emotions. First, he feels embarrassed for having insulted a young man of a superior social class. Second, he feels he may have lost an opportunity to make valuable acquaintance with a young man "who hasn't any friends or connections in London." Finally, he feels a bit ashamed of himself for having felt so contemptuous of all the unfortunate people he had been observing in the dusk.
The silliest thing that the young man did was to loose the cake of soap....and to forget the name of the hotel or the street in which it was in.