Last year, an organization called Wealth-X — "the world's leading ultra-high net-worth intelligence and prospecting firm" — issued a report from its lair in Singapore about what it calls "the looming wave of wealth transfers." Baby boomers are expected to play their part by succumbing to the looming wave of death — the Greatest Degeneration — and bequeathing $16 trillion to their children over the next three decades. For princes and princesses of American aristocracy, these bittersweet transactions hold little suspense. But for upper-middle-class Americans balancing mortgage payments, tuition bills and retirement plans on a brittle tower of monthly paychecks, this bounty looms with the promise of salvation. If you find yourself overanticipating such financial relief, take a break from the death watch to read Cynthia D'Aprix Sweeney's debut novel, "The Nest," a comedy of filial greed and affection. Here, in scenes both witty and tragic, is a warning about what comes of waiting for inherited affluence. The story revolves around the four Plumb siblings who have built their adult lives on the promise of a trust fund set up by their late father. (He was a chemist who made a fortune on diapers and feminine hygiene products at "the Dawn of the Absorbency Revolution.") The money he left behind — the nest — was intended only to be a "soupcon, a little something to sit atop their own, inevitable financial achievements," but a funny thing happened on the way to responsible parenting: While the nest grew into a vast fortune, the Plumb children accrued vast debts, knowing that when their little sister, Melody, turned 40, the vault would open and their bills, debts and mortgages would all be washed away. Certified financial advisers use a technical phrase to describe this plan: Counting Your Chickens Before They Hatch. Sure enough, we meet the Plumbs just as their eggs are about to be smashed. "The Nest" opens with a prologue in which handsome, chronically irresponsible Leo Plumb abandons his wife at a party, seduces a teenage waitress and totals his car during a sex act. Medical bills, legal fees and hush money effectively drain the nest from its once-impressive volume back down to a soupcon. Leo's siblings are apoplectic. Sweeney, a 55-year-old New Yorker who now lives in Los Angeles, knows these people well, and she captures them in short scenes that glow with the confidence of an experienced comic writer. A look back at pre-crash Leo shows him as the founder of a Gawker-like website that vomits up clickbait to keep advertisers swooning. After cashing out, "he'd gone for long walks and taught himself all about single-barrel whiskey. He read, quietly resenting anything he deemed good. He spent months designing a custom bike that he never rode." If that's not the voice of a wealthy layabout, it's the voice of someone who has been eavesdropping on them for years. The novel has just as much fun with the rest of these prodigal siblings, who insist in rising tones of panic that Leo replenish their exhausted trust fund posthaste. We meet Leo's brother, Jack, in the Campbell Apartment tavern in Grand Central as he's "sending his drink back because he believed the mint hadn't really been muddled. 'It was just dumped in there as if it were a garnish, not an ingredient." Their sister Bea is a chronically blocked writer who fears "the happy glimmer of recognition" in everyone she meets; she knows how quickly that look will decay into "the confused brow ... trying to summon a recent memory of her work, anything other than her early long-ago stories." Their little sister, Melody, is so manically determined to create the perfect home for her children that she "charted the time spent with each child, making sure to even it out as far as was humanly possible." Everybody knows never to mix money and family, which is great advice for anyone who has plenty of money and no family, but Sweeney is writing for the rest of us.