No one else writes fiction quite like Lydia Millet’s. She’s a wickedly funny satirist, yet her work has a warmth seldom found in satire. Even as she skewers fundamentalist evolution-deniers or reckless despoilers of the environment, she clings determinedly to the belief that people can be kind and good in surprising moments. For all the accuracy of her observations on the follies of American life, she refuses to be confined by traditional realism, demonstrating from Omnivores in 1996 to Magnificence in 2012 that her artistic range encompasses with equal comfort the achingly ordinary and the deeply strange.

Mermaids in Paradise has an ample helping of this unusual aggregate of qualities, conveyed in the marvelously distinctive voice of Deb, a sardonic Stanford MBA with a corner office and a house in Brentwood who as the novel opens is planning her wedding with equal parts amusement and alarm. Husband-to-be Chip’s honeymoon suggestions include “a shark- and stingray-feeding package, with round-trip airfare included, optimistically.” Best friend Gina throws her bachelorette party at an S&M fetish club. At least their choices are more interesting than those of her mother-in-law, who keeps trying to foist traditional wedding items like engraved favors on the vehemently unsentimental Deb. “Chip and I,” she states bluntly, “were no longer impressed, like so many gentle natives on the wrong end of the cargo-cult trade, by the magical wonder of the monogram.”

A domestic set-up with a political punchline: vintage Millet, and Deb and Chip haven’t even arrived in the British Virgin Islands. (They settle for a Caribbean honeymoon.) But in addition to some other stinging comments that flag Deb’s occasionally snooty social attitudes (about “people who believe that fossils are a trick” and “victims of the morbid obesity pandemic”), the opening chapter also previews the story’s emotional conflict. Kind-hearted Chip, whose father split when he was 10, tries to think the best of everyone and is particularly romantic about those average Americans he dubs “from the Heartland.” Gina, who “lives in a world of irony,” declines to have faith in anyone or anything, and average is a dirty word to her. (Heart might be too, after the lingering death of her mother when she was a kid.) They pull Deb in opposite directions, and she loves them both.

Both worldviews prove to have some validity once marine biologist Nancy spots mermaids while snorkeling in the reef off their island resort. Deb and Chip are among those she recruits to confirm her sighting and make an underwater video of the legendary fish-people (both male and female, though everyone refers to them as mermaids). “We’re the custodians of priceless knowledge,” Nancy exhorts the group as Chip hands out confidentiality agreements. “Not grubby profiteers who’ll go down in Wikipedia as destroyers of a race.” But some folks prefer profit: After a neighbor sees Nancy’s body carried away from her cabin—drowned in the bath, they tell him—the video camera and footage go missing, and members of the group start slinking away to Venture of Marvels, “the new mermaid tourism company … a wholly owned subsidiary of the multinational chain that also owned our resort.”

Only a forlorn band of eight—including our narrator and her spouse, of course—remains to resist this sinister plan to net the mermaids and display them as a tourist attraction in place of the dying reef. They’re an oddball bunch, including a Japanese TV personality and a former Navy SEAL whose respective talents come in handy as she broadcasts news of the mermaids’ existence, documented by the video he manages to surreptitiously retrieve. Matters are getting a lot more serious, although Deb still has enough sass to regret that, in the live footage of their confrontation with soldiers brought in by the hotel, “I was immortalized wearing [a] floral quasi-muumuu.”

She’s not laughing when the mermaid video prompts an online backlash from the Middle Americans Chip idealizes. “The mermaids were against God, the people of the Heartland said: the mermaids were unholy.” Soon the mermaid-haters acquire social network pages and begin disseminating violent messages: Hunt them, and put them down. This is a test of faith! “The virtual world was even worse than the real one,” Deb keens. “We were a roiling mass of opinion, most of it mean.”

It seems that Gina, who has flown in to help Deb, was right all along to warn that “people would disappoint you every time.” But that’s not the whole truth, as three dramatic and almost flagrantly implausible plot twists affirm that people can also choose to do the right thing. Sometimes, Millet suggests ever so tentatively, there are alternatives beyond delusional faith and self-protective cynicism, even though neither the mermaids’ farewell appearance nor a final, science-fictional plot twist offer much hope for humanity’s future.

Millet’s fury over the planetary consequences of our selfishness and arrogance is palpable in everything she writes, and she’s not above caricaturing her opponents; she’s a satirist, after all. But she’s so much more; at her best she approaches Shakespearean comedy in the clear-eyed, rueful humor with which she portrays her characters’ fumbling, imperfect attempts to love each other and the world around them. It gives her work an extraordinary poignancy, and makes each new novel by Lydia Millet a cause for celebration.