Emma can hardly believe it: a real horse all to herself - Mississippi, the mare of the late old Klipperbusch! Especially since Emma isn't even allowed to have a guinea pig at home. Such an amazing gift could only come from her grandmother Dolly. Her house is basically a shelter for animals: dogs, goats, cats, a ton of poultry, and now a horse too! These are definitely going to be exciting holidays - but! Because what happens next is something Emma never expected: strangely enough, Klipperbusch's nasty nephew suddenly wants Mississippi back at any cost. After all, he had sold this "annoying heirloom" to Dolly for a lot of money before. Could this be connected to Klipperbusch's mysterious will? And when Dolly's dogs go missing without a trace and a blackmail letter appears, an exciting race begins.