'A Good Person' is a murder mystery wrapped in a psychological thriller

“A Good Person,” Kirsten King’s riveting debut novel, is a murder mystery wrapped in a psychological thriller — set in Boston and told entirely from the perspective of Lillian, a memorable and memorably unreliable protagonist.

Lillian holds a mundane marketing job, has just turned 29 and is dating Henry, a risk analyst at State Street Bank.

Well, sort of dating him. Henry regularly uses his work as an excuse to get together only on certain weeknights and never on weekends. Even so, Lillian fantasizes about meeting his family and buying a house with him on Martha’s Vineyard.

What Lillian yearns for isn’t outrageous: a comfortable life with a loving relationship and an easy group of friends. But for her, it’s always out of reach. Lillian’s personality is a roiling blend of egoism and victimhood; she often presumes a strong bond of friendship or romance where even a weak one barely exists. King skillfully creates scenes that reveal Lillian’s skewed but weirdly compelling internal logic and the real-life reactions of those around her.

And yet Lillian also possesses a social antenna that pings when encountering compassion she can exploit, as with Jamie, her one friend from college, a woman who’s perpetually willing to lend Lillian money or an understanding ear. Or her boss Candace, whose “millennial guilt” about work, as Lillian sees it, prompts her to believe every excuse Lillian invents for a steadily filling calendar of missed workdays and project deadlines.

Throughout “A Good Person,” King drives the narrative with a style both lean and muscular and a tempo that keeps you avidly moving from one page to the next. It’s notable that King also writes for film and television; her credits include the 2022 movie “Crush” and the animated TV series “The Second Best Hospital in the Galaxy.” That experience may have honed the practice of taut pacing needed for a can’t-put-it-down thriller. It’s probably not a coincidence that bestselling authors of suspense novels, like Lee Child and Tim Sullivan, also had years of experience in television before turning to the written page.

Lillian’s fantasy future with Henry is suddenly demolished when he abruptly ends their relationship. She is outraged, thinking of how she “had spent the last four months crafting a specific version” of herself, the “cool girl who was Down for Anything” in bed and “who liked listening to Henry summarize all of the Dune books.”

Her anger, however, soon turns to horror when she learns Henry has been found dead outside a bar near his apartment.

That anger reignites when Lillian discovers Henry had been deceiving her. He’d been seeing someone else all along: Nora, his long-term girlfriend.

In a “Dear Reader” note at the front of the book, King says she is “fascinated by the way romantic relationships change people.” How women, especially, will mold themselves to more perfectly suit their partner to keep the romance going.

Not being able to be your true self around your partner is one thing. What if the person you’ve changed yourself for is not a good guy? “A Good Person” shrewdly explores all this, especially with the twist of a woman who, though wronged, is extremely flawed.

In employing an untrustworthy female protagonist as a vehicle to delve into consequential matters, “A Good Person” joins other novels (all published in 2025) like Marisa Kashino’s “Best Offer Wins” (the impossible real estate market), Julia Spiro’s “Such a Good Mom” (postpartum depression) and Donna Freitas’ “Her One Regret” (the fraught choice of motherhood).

Nora, less flawed but also wronged, is Lillian’s nightmare. She has attended the right schools (Nora and Henry met at Brown University), wears the right clothes, has a chic job (event planner for a trendy Cambridge-based company).

In short, as Lillian bitterly reflects, “the kind of girl finance guys in Boston love, the kind of woman they settle down with.” The opposite of her.

“A Good Person” captures the physical aspects of Greater Boston (areas like Allston, Mission Hill, Cambridge are nicely sketched out), and even more, it captures singular aspects of local culture, like the centuries-old Brahmin influence of subtle yet unyielding class distinctions like those that divide Nora and Lillian. It also wryly displays Boston’s big small-city vibes, as when Lillian mused that her appearance was “a solid Boston eight” and Henry’s was “a soft Boston seven” but neither of them would “even register on the Los Angeles or New York scales.”

As the murder investigation heats up, the paths of Lillian and Nora begin to cross in unexpected ways, connected by the fact that Henry was not the stand-up guy he appeared to be. In fact, sometimes he was kind of a terrible person. But so terrible he attracted his fate? Or was his fate simply to be the victim of random violence?

With Lillian, King has created a character who is convincingly disturbing, and places her in a world that smartly smudges the line between good and bad, aggressor and victim, real and unreal.

Kirsten King will be in conversation with author Jane Roper at Harvard Book Store on Friday, April 3. This event is free and no tickets are required.