Sandor is a large evening sailor from Transylvania. He is a talking bat with a notch in his left ear. All alone, Sandor lives in the farthest corner of the classroom in an old roller box. Right below him sits the boy Jendrik. He is not a good student and is often teased by his classmates. Sandor befriends him. Together, they uncover a big secret. A thief has buried a glittering chest at the castle ruins! Sandor and Jendrik find the treasure and embark on a turbulent adventure.