E ARC provided by Netgalley

Maya Mendoza loves to solve mysteries, even though it's gotten her in trouble with her former friend Jordan. When Maya asks to go to the restroom during class to check on her friend (and to get a hit of bubblegum), she and Jordan are caught in front of the contraband closet, where the school stores all of the toys, technology, and other distractions that get taken away from children. The principal sentences them to an after school detention, where they meet Ava Agarwal, a ten year old prodigy who runs a Happy Helpers business, as well as Clementine, who has moved to the school from a ritzier neighborhood. Jordan has had the school choir pitch pipe confiscated, and Clementine has lost her cell phone, so the group distracts the monitor and breaks into the closet... only to be caught again. The closet is empty, and unless they can find the culprit, the group will be in detention every day. Maya's parents are divorced, and her father has a girlfriend, Madge, who doesn't appreciate the 1940s detective films as much as her father does, but is a better cook, and her parents' inattentiveness gives her some leeway to investigate the case. Using Ava's Happy Helpers as a front, they give coupons to the suspects so they can sneak into their houses. They start with Johnny Persnicowitz, but find no evidence, and are hired to do someone's diorama for school, to clean bathrooms, and to play cards with someone's grandmother. None of their investigations pan out, although they get some leads to follow. A tagger named Frito seems a likely suspect until he turns out to be a fairly mild mannered (and a little bit cute) classmate named Seth. Suspecting Jordan's friend Kaylee makes checking her out difficult, but Maya spray paints her garage and then sneaks into her house while cleaning it up. Is she the culprit? Maya and her group won't rest until they find out who has stolen 40 years worth of contraband.
Strengths: Maya's love of a mystery causes a lot of tension with Jordan, and that kind of friend drama is definitely typical of middle school. The investigation is well constructed, and lets Maya and her fellow detainees talk to all manner of different students. My favorite part of the book was the father's girlfriend, Madge, who ends up picking Maya up from school one day after she gets in trouble, and is a very reasonable and supportive person. I'm curious to see what the next mystery will be.
Weaknesses: I cannot even imagine the wrath of a parent whose child's cell phone was taken away and not given back the same day! This would never happen at my school. If a student's phone is taken away, a parent is called IMMEDIATELY, and the parent has to pick up the phone. Phones are expensive! Also, if there is 40 years' worth of contraband, why does it get handed back to students at the end of the book after the mystery is solved? And why is the closet in the hallway and not in the office? This was not at all realistic, which made it hard for me to become invested in the story. There is some problematic language as well. I don't think my students use phrases like "take a leak", "other side of the tracks', or "broad" (which is highly offensive!).
What I really think: This is a good choice for readers who enjoyed the film noir highjinks in Tidhar's The Candy Mafia, Daneshvari's The League of Unexceptional Children, or Krosoczka's Platypus Police Squad.

The characters are amazing. Lots of simple lessons taught in an easy and entertaining way. Fun story.