This chapter leaves the narrator and follows his younger brother in London, where the brother is a medical student.
Also, be aware we are rewinding a few days, back to Saturday when the Martians were still just a threat to the Woking area.
Londoners get news of the Martians, though some of it is garbled. For instance, the Heat-Ray becomes a "quick-firing gun" (1.14.2).
Most of the Londoners are sure they're safe and so there isn't much worry over some distressing clues – like the telegraph system to the Woking area failing or the trains not going through to Woking on time on Saturday.
The narrator notes that he's read accounts in which London got all excited on Sunday with the news of the Martians, but from what he's been able find out, people generally went about their ordinary lives.
By contrast, the narrator's brother wants to make a change from his ordinary life – he wants to move toward the invasion.
However, as the day goes on, the alien invasion starts to affect people's lives. For example, people can't go out into the country for picnics, which probably ruins their days, but at least they aren't turned into charred corpses. Also, refugees flood into the city and the army moves out. (Neither the refugees nor the soldiers really blend in with people going around in their Sunday best.)
In order to get some info about the Martians, the narrator's brother buys an expensive newspaper – instead of the usual price of probably a penny, it costs three pennies. Although this newspaper describes the terrible Martian weapons, the newspaper's tone is "optimistic" (1.14.19), possibly because of how inflated the price is.
In London, you can hear the big guns firing at the Martians – at least, if you are in a small side alley you can. Otherwise the streets are so crowded and loud that you really can't hear much of anything but city clamor.
Although he's worried about the narrator, the narrator's brother goes to sleep on Sunday night, only to wake up early on Monday to an alarm going off. Apparently the Martians are coming and everyone else is politely – but quickly – leaving London to make room.
"London, which had gone to bed on Sunday night oblivious and inert, was awakened in the small hours of Monday morning to a vivid sense of danger" (1.14.44).
People are yelling about Black Smoke – capitalized, so you know it's going to be important, even if we don't know what it is yet.
Meanwhile, a newspaperman is running away from the city, selling his papers for a lot more than usual – "a grotesque mingling of profit and panic" (1.14.45).
From the paper, the brother learns that the Black Smoke is a type of poison gas. (This was before chemical warfare became a common part of war, so for people reading this book in 1898, this is something very new and terrible.) Also, there's a government announcement that everyone should get out of London.
The brother grabs his money and gets out. Hopefully he'll have enough moolah for another paper or two.