Wren Sterling has a problem. She knows she's super smart and a good friend, but no matter how hard she tries, she can't shake her reputation as a troublemaker. It feels like the only people who believe in her are her three best friends in the Renegade Girls Tinkering Club. She'd hoped middle school would be different, but when her inability to control her temper causes an accident, even her beloved tinkering club is no longer a safe haven.

She has to find a way to fix it. When her idea to start a business inventing and selling spy gadgets succeeds, it looks like she's finally done something right! But then the Club is accused of a crime. Can they use their own gadgets, and a little bit of trouble to solve the mystery? If they can find the real culprit, Wren may just discover she has a bright future after all. If they can't, she could lose her best friends forever.

"It's The Babysitter's Club meets MacGyver!"

Build your own SPY GADGETS! Instructions included in this charming story about friendship, middle school, and the Engineering Design Process for kids ages 8-12.