Gangsta Granny hits the exact sweet spot that made Roald Dahl famous: absurd characters, cartoonish adult authority figures, and a healthy dose of gross-out humor. Ben dreads spending Friday nights at his grandmother's house—endless Scrabble and cabbage soup—until he stumbles upon a tin full of diamonds and discovers she used to be an international jewel thief.

Behind the ridiculous Crown Jewels heist plot, David Walliams sneaks in a genuinely sweet message about intergenerational empathy. The book shows kids that older adults had full, adventurous lives before becoming someone's grandparent.

The only real heads-up is the ending. The book shifts tone sharply in the final act when Granny falls terminally ill and dies. It is handled gently and gives the story real heart, but parents should know it moves beyond simple comedy.