Bibi has not won a race against Tina for a long time. The two girls also find out the reason: Sabrina's old saddle is broken and hurts Bibi's favorite horse. It's a good thing that junk dealer Hannes is just coming to Martinshof with an old saddle made by a famous master. This saddle fits Sabrina like a glove, and she trades it for an old heirloom of Mrs. Martin. But then Count Falko von Falkenstein buys the saddle from Mrs. Martin for his collection. Bibi & Tina protest, but in vain. Bibi simply whishes the saddle back to Martinshof - but unfortunately together with the count! Of course, that means a lot of trouble. But then Bibi & Tina learn about a mystery.