Shortly before the summer break, Bibi is allowed to visit Tina's class, and ends up summoning her favorite mare Sabrina. The kids love it, but all the whinnying and laughing gets on their teacher's nerves. Thinking a little joke might lighten him up, Bibi casts a spell to make him whinny like a horse. But then the reverse spell won't work!

After a heavy storm, help is needed at Falkenstein Castle. Bibi and Tina take the carriage ponies Max and Moritz there to pull away fallen trees. But during the cleanup, the ponies suddenly disappear. Have they escaped or is this the work of a horse thief? Bibi, Tina and Alex have a suspicion!

What's the matter with Max and Moritz? The two carriage ponies easily overtake Bibi and Tina on their horses while racing. Then they effortlessly pull a broken train into the station! Bibi assures everyone that she did not use her magic on the pony twins. But where did their superpowers come from so suddenly?