If you’ve picked up a thriller in the last five years, you’ve probably seen A.J. Finn’s name on it. But not necessarily on the cover.

Since the publication of his blockbuster novel “The Woman in the Window” in 2018, Finn has become something of a serial blurber, adorning dozens of novels with his praise. “Loved every word,” he said of Richard Osman’s “The Thursday Murder Club.” He declared Alex Michaelides’s “The Silent Patient” “that rarest of beasts: the perfect thriller.” Of Nita Prose’s “The Mystery Guest” he gushed, “Wise and winning and altogether wondrous,” adding: “I was nearly hugging myself as I turned the pages of this splendid novel.”

Meanwhile, Finn’s next novel — the second part of the two-book, $2 million deal he made with William Morrow in 2016 — remained a work in progress. Expected to be published in 2020, the book, “End of Story,” finally landed in stores last week.

The question is: Will it be enough to save Finn’s reputation? Before answering, I need to explain the unexpected plot twist that preceded its publication.

“The Woman in the Window” was a smash hit that put its witty, camera-ready author on the cusp of celebrityhood. The book — a domestic suspense tale about an agoraphobic child psychologist who believes she has witnessed a murder — debuted at No. 1 on the New York Times bestseller list and went on to sell millions of copies worldwide. Stephen King called it “delightful and chilling”; Louise Penny declared it a “tour de force.” Translated into more than 40 languages, the novel was made into a film with Amy Adams, Gary Oldman and Julianne Moore. It even inspired a spoof, “The Woman in the House Across the Street From the Girl in the Window,” a Netflix series starring Kristen Bell.

But something funny happened on the way to fame. In early 2019, an exposé in the New Yorker portrayed Finn, whose real name is Dan Mallory, as the kind of unreliable narrator you might find in an A.J. Finn novel. The article detailed a trail of less-than-true stories Mallory had told about himself over the years: that he had a doctorate from Oxford; that his mother had died of cancer; that he had a brain tumor; that his brother had died by suicide. Colleagues reported that during his decade as a book editor, Mallory used these struggles to elicit sympathy, further his career and vanish when things got awkward. At one point, when Mallory was working in New York at Morrow, he stopped coming into the office, a disappearance that was explained away by a series of emails from a mysterious sender claiming to be Mallory’s now-alive brother but sounding a lot like Mallory himself.

Mallory eventually confessed to his fibs, sort of. Through a publicist’s statement to the New Yorker, he said that he had “severe bipolar II disorder,” which caused “delusional thoughts” and “memory problems.” Mallory’s psychiatrist told the magazine that the writer’s experience with his mother’s (real but not fatal) bout with breast cancer had contributed to his expressing “‘somatic complaints, fears, and preoccupations,’ including about cancer.” Mallory said he was “utterly terrified of what people would think of me if they knew” about his mental health problems. “Dissembling seemed the easier path. … I’m sorry to have taken, or be seen to have taken, advantage of anyone else’s goodwill.” Reaction to this expression of regret-cum-justification was mixed; some, including a letter-writer to the New Yorker with bipolar disorder, criticized the author for further stigmatizing the disease: “It was upsetting. … Mental illness does not make you a liar, a scammer, or a cheat.”

Given this heavy baggage, to consider “End of Story” on its own merits poses a challenge. Let’s try.

As a commercial suspense novel, “The Woman in the Window” — at least for the first 200 pages — is quite entertaining, if derivative for anyone who’s seen “Rear Window,” or any Hitchcock, for that matter. (Finn also defended himself against accusations that he had plagiarized plot points of Sarah A. Denzil’s “Saving April,” with he and his agent saying Finn’s book had been plotted before Denzil wrote her book, which Finn never read.) Told in the present tense, in short sentences and chapters, the tale speeds along. At its center is the distraught, pill-popping child psychiatrist Anna Fox, who is not as she appears.

In the heyday of thrillers with unreliable narrators — see “The Girl on the Train” and “Gone Girl” — Fox was a master dupe. She loved her merlot (a detail mocked to brilliant comic effect in the Kristen Bell parody) and staring out the window (like Grace Kelly but in a ragged bathrobe) at her neighbors, who were up to something but not what she thought.

What the plot lacks in plausibility, it makes up for in the zippy immediacy of the writing, even when it patters on too long, collecting a few odd descriptions along the way, as when a phone rings: “My head swivels, almost back to front, like an owl, and the camera drops to my lap. The sound is behind me, but my phone is in my hand. It’s the landline. … Another ring. And another. I shrivel against the glass, wilt there in the cold. I imagine the rooms of my house, one by one, throbbing with that noise.” Still, Anna is a compelling character (“I feel as though I’m falling through my own mind”), and readers rooted for her even if we knew she probably wasn’t telling the truth.

“End of Story” is written in the same staccato style. The first page ends: “A breath. Then that scream. They’ve found her.”

But things get leaden right away. The setup is complicated — as one character says, “There’s too much time to keep track of.” Nicky Hunter, the book’s protagonist, is a young journalist hired by a dying mystery writer named Sebastian Trapp to write his biography (the pair met as pen pals). Trapp invites Nicky to live at his mansion in San Francisco while she writes. Trapp, called “the champion deceiver” (wink, wink) by critics, writes novels featuring a “gentleman English sleuth” named Simon St. John. Trapp is also a murder suspect. Years before, his first wife, Hope, and his son Cole disappeared and are presumed dead. How Trapp figures into this puzzle is one of the questions Nicky hopes to resolve while researching her book.

Sleeping in the bedroom once occupied by young Cole, Nicky gets to know various members of the Trapp family: Sebastian’s bitter daughter Madeleine (“her hair is careless and blond, her shoulders round”), his beautiful second wife (“fortysomething, lavish lashes and Cupid’s-bow lips”), his handsome, troubled nephew (“six feet of built-to-last, muscles bulging within his sleeves”). All of them think and speak in a similar way — droll, coy, urbane — which is to say with the same studied cleverness that Mallory deploys in interviews. Even Sebastian’s dog, Watson, is a French bulldog, the breed favored by Mallory. And then there’s this comment by a bit character late in the book: “Moral indignation is envy with a halo.” Could that be Finn throwing shade on his critics?

The plot drags on — the phrase “the plot thickens” appears without obvious irony. At times the book reads like a dime-store romance novel: “Up and across. The man is vast, an eclipse in coat and tie, pink linen shirt taut around his belly, like the skin of some unwholesome fruit. Black eyes lurking beneath zigzag brows. Face the color of rare beef.” (Thank you, but I think I’ll have the chicken.) Elsewhere, you can almost see Finn consulting a thesaurus. “You absquatulated,” Nicky says to Madeleine, whose desk is “a dainty escritoire that chafes her thighs.” At one point, books are “rutilant in the light.” And the ending, which I shall not spoil, raises more questions than it answers.

Finn drops heavy references to the works of literary greats: Agatha Christie and Alexandre Dumas, “The Count of Monte Cristo” in particular. The epigraph is from “Bleak House.” A copy of “Rebecca” is the key to opening the door to a hidden room. The book includes a note on sources, citing Raymond Chandler and Dorothy Sayers, among others. Perhaps the purpose is to protect himself from another accusation of plagiarism, though it also comes off as rather self-aggrandizing: Does he think his words would be confused with those of Arthur Conan Doyle?

Let me end the suspense here: Even readers looking past Finn’s personal woes — or those looking at them and wishing him well anyway — will quickly be hoping for end of story.

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End of Story

By A.J. Finn

William Morrow. 408 pp. $37