The Mystery of the Ancient Grotto

Peggy, Mike, Nora, and Jack are spending their vacation by the sea, in a picturesque place surrounded by caves and cliffs. One day, while walking on the beach, they discovered a rock formation, and inside it – a passage to an abandoned house on the cliff. According to legend, this house was once a hideout for smugglers and spies. What secrets does it hold now? The kids decide they must find out. They are in for many amazing discoveries…