Olive loved visits to her grandparents. Their old house smelled of dried apples, and the attic always tempted her to have a look in there. This year, she came along with her younger brother, Kuba. Exploring the nooks and crannies of the house together became their secret mission. One afternoon, when the adults were relaxing after lunch, Oliwia persuaded Kuba to take a trip to the attic. For a while, they had to tread carefully up creaking stairs until they reached a place full of trunks, old dolls and dusty books. Kuba wanted to go back straight away, but Olive noticed something unusual: in the very corner, underneath the piles of newspapers, a corner of a mysterious casket was sticking out. It was heavy, decorated with strange, faded patterns. The lock was held in place by a miniature keyless padlock. "See!" - whispered an excited Olive. "There's something written here!" From the chipped letters she struggled to read: "He who opens it will learn the secret of the family." Suddenly, a rustling sound came from behind the bookshelves. Cuba squeezed his sister's hand. "Why don't we go back?" - he whispered frightened. Olive, however, could not take her eyes off the mysterious casket. What was hidden in it? Who had left it in the attic? And were they really the only ones there?