I Read The World’s Greatest Detective, Here’s My Thoughts
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There’s something irresistible about a good cozy mystery that just hits. And when it’s one with sharp dialogue, offbeat dynamics, and just enough murder to keep you second-guessing every page, it becomes one you recommend to everyone. I picked up The World’s Greatest Detective and Her Just Okay Assistant, hoping for a clever, character-driven mystery book, and what I got was a wildly fun ride through one of the most memorable cozy mysteries I’ve read in a while. In this post, I’m diving into my full thoughts on the cozy mystery book everyone’s been buzzing about.
Whether you’re deep into your favorite cozy mystery series or just browsing for mystery books with quirky vibes, complicated crime scenes, and dry humor, this one absolutely deserves a moment on your shelf. And, if you’re searching for your next cozy, need a break from heavy plots, or just want a book that balances romance, tension, and comedy, this edition might be the one.
Keep reading for my honest take on the story, the characters, and whether this new series earns a spot on your must-read mystery cozy list.
Title: The World’s Greatest Detective and Her Just Okay Assistant
Author: Liza Tully
Publisher: Berkley
Format: EBook/Physical
Genre: Mystery, Cozy Mystery
Release Date: July 8, 2025
Pages: 400
Star Rating: 4 stars
Spice Rating: 0 chili peppers
The World’s Greatest Detective Finds A Just Okay Assistant…
In The World’s Greatest Detective and Her Just Okay Assistant, we’re partnered with investigator Aubrey Merritt, the brilliant boomer detective known for her no-nonsense approach to crime, and her newly hired—somewhat unexpectedly—okay assistant, Olivia Blunt. Honestly, no one is more surprised than Olivia herself (and the reader) when she lands the job. But from the moment she steps into Merritt’s world of tedious computer work and sharp-edged logic, it’s clear Olivia is in over her head. Still, something is endearing about her determination.
What follows is a case that begins at a sixty-fifth birthday party. Victoria Summersworth’s sixty-fifth, to be exact. A happy woman and matriarch of the preeminent Summersworth family, who is found dead after falling over her balcony railing into the rocky edge of Lake Champlain. The police ruled it a suicide, but daughter Haley thinks otherwise. And Olivia? She’s desperate to prove she’s capable of handling the whole detective thing. She wants—no, needs—this to be her moment.
Here’s the thing: the mystery is good. Really good. The mystery itself is intriguing—layered with just enough secrets, family tension, and strange behavior to keep you invested. Clues unravel bit by bit, and renowned investigator Aubrey has the kind of observational precision that makes everything make sense, even when the evidence seems mundane. It’s not flashy or shocking, but it’s constructed with care. As the clues unfold, so do the cracks beneath the surface of the family’s pristine image.
“She’s testing you,” he amended.
The pacing keeps you engaged, and each breadcrumb left behind feels intentional. It’s immersive in the way that makes the dialogue melt off the page. Liza Tully has created a dynamic duo that’s frustrating and funny, stubborn and sharp. It’s a classic whodunit, like playing Clue with real consequences (I wonder if that was the inspiration). If you’re someone who reads cozy mystery books for the satisfaction of putting the puzzle together piece by piece, this book delivers. I flew through it in two sittings. It’s that rare kind of cozy that’s digestible but doesn’t feel hollow. Tully’s writing has a quiet confidence. Nothing showy, but layered with the kind of dry humor and slow-building tension that sneaks up on you.
But this isn’t Merritt’s story—it’s Olivia’s. And Olivia… is frustrating. At times, deeply so. She’s impulsive and impatient, driven not by instinct but ego. Her desire to “solve” the murder and impress Merritt sends her spiraling into false connections and misguided assumptions. She overlooks vital gaps, ignores Merritt’s repeated guidance, and often dismisses entire angles simply because they don’t align with her rushed narrative.
But let’s be honest: Aubrey Merritt is the reason I stayed. She’s sharp, witty, and knows how to slice through emotional noise to get to the heart of a situation. Her ability to see—to point out what others miss, especially Olivia—is quietly masterful. She reminds me of the best kind of brilliant detective, delivering insight with just enough sting. She doesn’t care about being liked; she cares about being right.
“I’m not a talentless wannabe. I’m different.”
Olivia, on the other hand, is the book’s emotional engine(and did I mention its biggest frustration). Her need to prove herself makes her reckless. She rushes through the investigation, makes one apparent mistake after another, and often refuses to pause and consider what’s not being said. Even after repeated conversations with Merritt, she’s defensive and stubborn. Her refusal to search Victoria’s room because she “doesn’t want to go through a dead woman’s things” made me want to shout. You want to be a detective, girl? Woman up. This is the job.
And yet… I get her. She’s ambitious. She’s scared. She doesn’t want to fail at the one thing she’s built her hopes around. Her mistakes don’t make her a bad character; they make her real. I just wish there had been more growth by the 60% mark. Still, watching her flounder while Merritt remains composed creates a dynamic that works. It’s frustrating, yes, but it’s also intentional. Tully explores the clash between ego and experience, between emotion and observation. That tension makes the book’s mystery more than just a game of “whodunnit.” It becomes a character study.
“People loved her,” Clemmons said without hesitation.
By the time we reach the reveal, though, the momentum falters. What should’ve landed with a gasp felt more like a shrug. I wasn’t shocked. I wasn’t even that interested. Maybe it was intentional misdirection. Maybe the book’s strength was never in the ending, but in the search itself. But by the final 40 pages, I felt disconnected.
Still, I’d recommend this to anyone looking for a smart, fast-paced mystery cozy that straddles the line between character drama and crime-solving content. It’s a great Fall read, and a solid pick for your next book club meeting. Especially if you love diving into character flaws and asking, “Why did they do that?” If Tully writes another in this series, I’d read it. I want to see what Olivia does next. I want to watch her finally slow down and see. Because, despite my frustrations with her, I’m rooting for her.
If you love flawed characters, twisty whodunnits, and emotionally layered reads, join my monthly letter for even more bookish thoughts and recommendations.
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