Dennis and Gnasher must find Dennis's missing little sister, Bea, before his parents return from a wedding and discover she's gone. Dennis and his friend Harsha attempt to avoid babysitters by taking on the task themselves, but their plan goes awry when Bea disappears. Now, they, along with Rubi, must race across Beanotown, following the chaotic trail Bea leaves behind, to locate her before their parents arrive home. The narrative unfolds as an adventure story accompanied by humorous illustrations.

This book is presented as the sixth installment in a humorous illustrated series for children aged 7-10. The premise suggests a lighthearted adventure with a focus on comedic situations arising from a child's disappearance and the subsequent search. The inclusion of characters like Dennis, Gnasher, and Bea, along with the 'Beano' branding, indicates a target audience familiar with the comic's style of humor and character dynamics. The narrative is designed to be engaging for young readers through its fast-paced plot and visual elements.