The following books will have middle-grade mystery fans puzzling through clues to determine "Whodunit?" See also Marthe Jocelyn’s upcoming article about Agatha Christie in the May/June Magazine — and what The Horn Book thought of Knives Out.

Aggie Morton, Mystery Queen: The Body Under the Piano
by Marthe Jocelyn; illus. by Isabelle Follath
Intermediate    Tundra    325 pp.    g
2/20    978-0-7352-6546-2    $15.99
e-book ed.  978-0-77352-6547-9    $9.99

In 1902 Torquay, England, twelve-year-old Aggie befriends a Belgian refugee, Hector Perot, and investigates a murder roiling the town. When Mrs. Eversham, known throughout town for her sharp tongue and bad temper, is found dead on the floor of her sister-in-law’s dance studio, Miss Marianne is the prime suspect. Aggie is certain her beloved dance teacher is innocent, so she evades adult oversight to solve the crime (with Hector’s help). Plenty of red herrings keep Aggie discovering and discarding clues, and she finds as her investigation intensifies that the adults of Torquay appreciate her assistance less than they should. The young characters have a good deal of autonomy, driving a plot where parents, grandparents, and police officers are merely tolerated presences in the children’s world. Aggie, an observant outsider, is an engaging protagonist, with wide-eyed curiosity balanced by acute insights about many of the people in her community. Jocelyn keeps readers guessing throughout the book, but the eventual reveal of the perpetrator is believable, carefully clued, and satisfying. A solid dose of tart wit (“Irma Eversham will be honored by more people as she enters her eternal slumber than she spoke to civilly in all of 1902”) makes it an extra-enjoyable read; readers will eagerly anticipate the (hinted-at) further adventures of Aggie and Hector. An author’s note explains that the story is inspired by Agatha Christie’s childhood, and while Christie fans may pick up on the many subtle references to her books and characters (Hercule Poirot, Miss Marple), the mystery stands on its own. SARAH RETTGER

The Thief Knot: A Greenglass House Story
by Kate Milford; illus. by Jaime Zollars
Intermediate, Middle School    Clarion    456 pp.
1/20    978-1-328-46689-1    $17.99
e-book ed.  978-0-358-16427-2    $9.99

In the Liberty, a part of Nagspeake (Greenglass House, rev. 9/14, and sequels) where retired rogues and smugglers find sanctuary from the long arm of the law, Marzana takes it upon herself to solve a mystery after her mother is asked to find a kidnapping victim. Hoping to help rescue the missing girl, and despite her extreme social anxiety, Marzana assembles a team (or “knot”) of her own: her best friend and codebreaker Nialla; a magician named J. J.; Ciro, a “camofleur,” or expert in hiding things in plain sight; and Meddy, the ghost from Greenglass House who arrives via parcel post. The team makes progress following up on several clues, but kidnapping isn’t a game, and Marzana’s parents are furious when they discover the knot members putting themselves in danger. This entry shows all of Milford’s strengths: theme-expanding stories within stories, a thrilling genre fusion, swashbuckling technical mastery (here, lock-picking, cryptography, and sleight-of-hand magic), a vocabulary to delight the word-nerds, and an invented world real enough to live in. Delivering layers upon layers, convincing characters who succeed despite their emotional challenges, and a brain-tingling mystery that unfolds at just the right speed, this ghostly fantasy-adventure is a humdinger of a good read. ANITA L. BURKAM

The Peacock Detectives
by Carly Nugent
Intermediate, Middle School    Harper/HarperCollins    282 pp.
1/20    978-0-06-289670-4    $16.99
e-book ed.  978-0-06-289672-8    $7.99

Cassie is enlisted by her neighbors to find their missing peacocks — again — because of her skill at noticing details. But there are plenty of other things for the Australian almost-twelve-year-old aspiring writer to notice, and the story Cassie narrates ends up taking a broader focus, encompassing her parents’ separation, her grandfather’s illness, her older sister’s embrace of Buddhism, and her father’s and her own mental health (like Cassie, he struggles with depression). When Cassie’s best friend runs away, it’s Cassie who figures out where to follow him, but she is surprised to encounter the school bully, who’s also running away from home, along the way. Readers observe Cassie’s world along with her; her narration makes clear that she doesn’t always understand what’s happening but sees enough to know when secrets are being kept from her (though references, in her often-funny voice, to the story elements she’s employing show her trying to feel in control: “In this story I’m going to try to give you enough details so that you can understand, but not so many that you get bored and stop reading and go to the park or the zoo instead”). The lost peacocks are secondary; friendship and family come first, making this detective story a good choice for any realistic fiction fan, mystery lover or not. SHOSHANA FLAX

York: The Clockwork Ghost
by Laura Ruby
Middle School    Walden Pond/HarperCollins    449 pp.
5/19    978-0-06-230696-8    $17.99
e-book ed.  978-0-06-230698-2    $7.99

Despite the destruction of their beloved apartment building at the end of the previous book (York: The Shadow Cipher, rev. 5/17), codebreaking twins Theo and Tess Biedermann, along with artistic puzzle-solver Jaime Cruz, are more committed to solving the impossible-seeming Morningstarr Cipher than ever. Following a complicated trail of clues, which stitches the technologically advanced present to an enigmatic past (both their own and that of the book’s alternate New York City setting), the tweens solve puzzles — bringing stone eagles to life, digging up graves, and uncovering less-than-savory genetic experiments as they go. But these three are not the only ones pursuing the treasure that supposedly awaits at the end of the Cipher, and danger is rapidly closing in. A few narrative contrivances aside, this second installment in Ruby’s steampunk mystery series should delight and enthrall fans. ANASTASIA M. COLLINS

From the March 2020 issue of Notes from the Horn Book.