The Newest Crop of Sleuths for Kids Members of the criminal underworld, beware the little children. They've been on to you for years, and the number of mystery-loving young readers seems only to grow. Now to the ranks of Encyclopedia Brown and Cam Jansen comes the newest crop of budding Hercule Poirots: two are American, one is from Botswana, one gang hails from England, and two are Canadians with twitchy noses. The one thing they have in common is that each provides the seeds to understanding how a perfectly average child (or rabbit) might go about becoming a sleuth when baddies need foiling. The heroes of "Mr. and Mrs. Bunny - Detectives Extraordinaire!" are out to foil a group of dastardly foxes. Precious Ramotswe's Very First Case By Alexander McCall Smith Illustrated by Iain McIntosh 73 pp. Anchor Books. Paper, $6.99. Middle grade; ages 7 to 10 By Jane O'Connor Illustrated by Robin Preiss Glasser Harper/HarperCollins Publishers. $9.99. Look Into My Eyes By Lauren Child Candlewick Press. $16.99. Middle grade; ages 9 to 12 And How They Were Captured by the Daring Detectives of the New Cut Gang By Philip Pullman Illustrated by Martin Brown Alfred A. Knopf. $16.99. Middle grade; ages 10 to 14 By Polly Horvath Illustrated by Sophie Blackall Schwartz & Wade. $16.99. Middle grade; ages 8 to 12 While it's hardly Alexander McCall Smith's first work for children, "The Great Cake Mystery" uses a particularly interesting approach. McCall Smith's early chapter book travels back in time to introduce Precious Ramotswe, the protagonist in his "No. 1 Ladies" Detective Agency" series, when she was just a child herself. "The Great Cake Mystery" recounts Precious" first case ever: a hungry thief is lifting treats and delicious tidbits kept in the children's belongings in her classroom. Though the book is gorgeously illustrated by the remarkably talented Iain McIntosh, McCall Smith, alas, does not seem entirely comfortable writing for a younger audience. Characters often explain things that would be entirely obvious to them, and chapter breaks are unnervingly sporadic. The result is a beautiful-­looking book that fills a real need for detective stories featuring characters who are anything other than white, but one that could have been stronger. Another entry into this genre also features a character with a serious built-in fan base. Yet where McCall Smith writes younger, Jane O'Connor goes for older readers. Fancy Nancy is an undisputed picture-book and early-reader phenomenon, so perhaps it was only a matter of time before her creators started working her into chapter books. It's tempting to write off "Nancy Clancy, Super Sleuth" as a bold attempt to siphon additional cash from little girls" parents. However, bedazzled magnifying glasses aside, "Super Sleuth" is quite well done. In their first outing as detectives, Nancy and her best friend, Bree, discover two mini-­mysteries (one involving a guilty friend, the other a missing marble) and through believable and clever investigative work manage to solve both. O'Connor, a children's books editor in her own right, has a fine ear for dialogue and includes details that will amuse parents roped into reading this at bedtime. You can't write this one off. Just as Nancy spins off into a series for children who might otherwise outgrow her, so does Clarice Bean morph into Ruby Redfort. Fans of Lauren Child's "Clarice Bean" books know by now how much Clarice adores reading a mystery series starring a girl named Ruby Redfort. With "Ruby Redfort: Look Into My Eyes," those books-within-the-books are now a reality. Here, the code-cracking genius Ruby is recruited by the secret agency Spectrum to help foil a bank heist and protect a rare jade statue in a story that clearly draws inspiration from the hard-boiled American crime novels of yore. Children must therefore get past characters calling one another "kid," "sweetheart," "lady," and a whole host of outtas, wannas and gottas. Child is British, and her awe of American vernacular shows. Though the book is a nice pastiche of the spy genre for younger readers, sluggish sections in which Ruby reads newspapers may lose some. Child sets her story in an imagined world where spy gadgets are abundant but cellphones and the Internet seem not to exist. When a phone number is listed as KLondike 5-1212, the jig is officially up. A more reliable method of doing away with technology is simply to place a story in the past - the distant past, if at all possible. Though known best to Americans for his work on the deadly serious "Dark Materials" books, Philip Pullman taps into his funny side with the wholly lighthearted "Two Crafty Criminals!," a set of capers previously published in Britain in 1994 and "95 but appearing here for the first time. In the late-19th-­century London borough of Lambeth, a crew of kids calling themselves the New Cut Gang encounter two distinct mysteries in separate stories. In the first, someone is spreading counterfeit money and it's up to the Gang to use a mannequin - an easily manipulated chestnut man - and a bit of ambergris to thwart the villain. In the second, someone has stolen the gas fitters" silver and the Gang manages to save the day thanks to a strongman, a bowler hat and the Prince of Wales himself. Where Child attempts an American voice with mixed results, Pullman fully embraces his English roots, which means children must tolerate references to everything from shillings to cricket without explanation. Once the stories hit their stride, they prove to be a hoot, but they may require patience to get there. Crossing back to Canada, we find the loosest mystery of the bunch. Polly Horvath has never struck me as an author who cares one jot what people think of her, and "Mr. and Mrs. Bunny - Detectives Extraordinaire!" does little to change this opinion. Raised by members of the counterculture, the perfectly sensible (and human) Madeline is stunned when her parents are kidnapped by what appears to be a car full of dastardly foxes. To her aid come Mr. and Mrs. Bunny, a pair of rabbits who have recently taken up detective work as their latest hobby. They may initially be more in love with the idea of wearing fedoras than with actual detecting, but they are Madeline's best hope. As with "Two Crafty Criminals!," readers will have to slog through language that isn't particularly child-friendly, in this case involving an alt-hippie lifestyle's references and phrasings. Yet if they make it past the first chapter, they're in the clear - everything thereafter is quite amusing. Horvath overdoes the winks to adult readers, but her fuzzy detectives will give younger readers something they can readily grasp and enjoy. Origin stories one and all, these introductory detective books won't necessarily supplant the established Nancy Drew or Jigsaw Jones in a child's affections. But they'll almost certainly sate a craving for bite-size mysteries. Elizabeth Bird is the New York Public Library's youth materials specialist. She is collaborating on a book about the true stories behind popular children's books.