During the summer holidays, grandma and grandpa come over to babysit again. Tiffany, Max and Luisa now also know who should look after whom. And yet they leave grandpa alone in the kitchen. Well, and grandpa puts the super cool new retro water heater on the stove and then he turns on the plate. It's just an accident, but it's still not a good idea: The kettle starts to melt, so it stinks up the whole house and everyone has to stay in the garden overnight. Against all odds, it actually turns out to be a lot of fun - with a table tennis tournament, a water fight, a campfire and scary stories about kettles. The latest children's book by Marc-Uwe Kling following the orderers "The Day Grandma Broke the Internet" and "The NO Horn". With incredibly funny illustrations by Astrid Henn.