Communication breakdown lies at the heart of A Handful of Dust. English landed gentry Tony and Brenda’s marriage collapses because of a mutual failure to communicate: Brenda conceals her real feelings about Hetton, Tony’s ancestral estate (“[…] so appallingly ugly. Only I’d rather die than say that to Tony”), initially to protect Tony’s feelings, but her concealment breeds boredom and resentment that evolves into more malign deception in the form of her affair with John Beaver. For his part, Tony’s obliviousness to Brenda’s clearly dissatisfied behavior leaves him blindsided by the affair that everyone else in their scene finds obvious.
Yet the novel registers a communicative collapse that runs deeper than just an individual marriage. Waugh invokes this theme through the ubiquitous presence of the telephone. At the time Waugh was writing, the early 1930s, the telephone was still a relatively recent invention and had only just begun to become widespread in private homes. It’s important to keep this novelty in mind to appreciate the profound disruption in normal lines of communication that A Handful of Dust seeks to depict. Telephones both invade the privacy one formerly enjoyed at home and breed alienation by offering a cheap substitute for human contact (“Why did you go all the way to London to telephone her?...Why, daddy?”). By creating distance in the illusory guise of nearness, Waugh implies, telephones increase “communication” while emptying it of meaning.
Ultimately, the telephone’s assault on communication merely symbolizes a deeper rupture: Brenda and Tony’s post-WWI generation have been cut off from their history and themselves. Through the deterioration of Brenda and Tony’s marriage and the generational alienation it reflects, Waugh suggests that rapid modernization has severed people’s line of contact with the past and accordingly blocked them off from the personal depths that such contact is meant to stir. People thus grow blunted, shallow, and cruel. Tony’s fate literalizes this total communicative collapse, trapped in a foreign jungle and without hope of contacting anyone who could help him.
Communication Breakdown and the Loss of Meaning ThemeTracker

Communication Breakdown and the Loss of Meaning Quotes in A Handful of Dust
[Rev. Tendril’s] sermons had been composed in his more active days for delivery at the garrison chapel; he had done nothing to adapt them to the changed conditions of his ministry and they mostly concluded with some reference to homes and dear ones far away. The villagers did not find this in any way surprising. Few of the things said in church seemed to have any particular reference to themselves. They enjoyed their vicar's sermons very much and they knew that when he began about their distant homes, it was time to be dusting their knees and feeling for their umbrellas.
“But don't you like the house?”
“Me? I detest it... at least I don't mean that really, but I do wish sometimes that it wasn't all, every bit of it, so appallingly ugly. Only I'd die rather than say that to Tony. We could never live anywhere else, of course.”
“What's all the news?”
“Ben's put the rail up ever so high and Thunderclap and I jumped it six times yesterday and six times again to-day and two more of the fish in the little pond are dead, floating upside down all swollen and nanny burnt her finger on the kettle yesterday and daddy and I saw a fox just as near as anything and he sat quite still and then went away into the wood and I began drawing a picture of a battle only I couldn't finish it because the paints weren't right and the grey carthorse the one that had worms is quite well again”
“Nothing much has happened,” said Tony. “We've missed you. What did you find to do in London all this time?”
But with the exception of her sister's, opinion was greatly in favour of Brenda's adventure. The morning telephone buzzed with news of her; even people with whom she had the barest acquaintance were delighted to relate that they had seen her and Beaver the evening before at a restaurant or cinema. It had been an autumn of very sparse and meagre romance; only the most obvious people had parted or come together, and Brenda was filling a want long felt by those whose simple, vicarious pleasure it was to discuss the subject in bed over the telephone […] The choice of Beaver raised the whole escapade into a realm of poetry for Polly and Daisy and Angela and all the gang of gossips.
“How difficult it is for us,” he began, blandly surveying his congregation, who coughed into their mufflers and chafed their chilblains under their woolen gloves, “to realize that this is indeed Christmas. Instead of the glowing log fire and windows tight shuttered against the drifting snow, we have only the harsh glare of an alien sun; instead of the happy circle of loved faces, of home and family, we have the uncomprehending stares of the subjugated, though no doubt grateful, heathen. Instead of the placid ox and ass of Bethlehem,” said the vicar, slightly losing the thread of his comparisons, “we have for companions the ravening tiger and the exotic camel, the furtive jackal and the ponderous elephant...” And so on, through the pages of faded manuscript.
“You know there wasn't really much for her to do all the time at Hetton. Of course she'd rather die than admit it, but I believe she got a bit bored there sometimes. I've been thinking it over and that's the conclusion I came to. Brenda must have been bored…”
“Nothing could have been more fortunate,” Brenda said. “If I know Tony, he’ll be tortured with guilt for weeks to come.”
“But you can telephone her from here, can't you, daddy? Why did you go all the way to London to telephone her?... Why, daddy?”
“It would take too long to explain.”
“This has been a jolly weekend”
“I thought you were enjoying it”
“Just like the old times—before the economics began”
“I only wanted to see [Rev. Tendril] about arrangements. He tried to be comforting. It was very painful… after all the last thing one wants to talk about at a time like this is religion.”
She frowned, not at once taking in what he was saying. “John… John Andrew… I… Oh thank God…” Then she burst into tears.
“But it’s not true, is it?”
“Yes, I’m afraid it is. Everyone has known for some time.”
But it was several days before Tony fully realized what it meant. He had got into a habit of loving and trusting Brenda.
“How’s the old boy taking it?”
“Not so well. It makes me feel rather a beast,” said Brenda.
[Tony] reminded himself that phantasmagoric, and even gruesome as the situation might seem to him, he was nevertheless a host, so that he knocked at the communicating door and passed with a calm manner into his guest's room; for a month now he had lived in a world suddenly bereft of order; it was as though the whole reasonable and decent constitution of things, the sum of all he had experienced or learned to expect, were an inconspicuous, inconsiderable object mislaid somewhere on the dressing table; no outrageous circumstance in which he found himself, no new, mad thing brought to his notice, could add a jot to the all-encompassing chaos that shrieked about his ears.
He hung up the receiver and went back to the smoking-room. His mind had suddenly become clearer on many points that had puzzled him. A whole Gothic world had come to grief... there was now no armour glittering through the forest glades, no embroidered feet on the green sward; the cream and dappled unicorns had fled...
“You’re the explorer, aren’t you?”
“Yes, come to think of it, I suppose I am.”
“Is it absolutely safe?”
“Oh, I imagine so. The whole world is civilized now, isn’t it—charabancs and Cook’s offices everywhere.”
“From now onwards the map is useless to us,” said Dr. Messinger with relish.
“I will tell you what I have learned in the forest, where time is different. There is no City. Mrs. Beaver has covered it with chromium plating and converted it into flats.”
“Do you believe in God?”
“I suppose so. I’ve never really thought about it much.”