The Boxcar Children have entered the Ruby Hollow Gem Mine's annual gem-hunting competition. With a little instruction and the right gear, the Aldens have everything they need to become real rock hounds They have a natural talent for rock-finding, and it's not long before Jessie makes a fabulous find. But before she can enter her ruby in the competition, it disappears Could there be a thief at the mine? Now, instead of digging for rocks, the Aldens are digging for clues. Who wants to win the contest so much that they would steal from the Aldens? The children don't know, but they're determined to find out


The Boxcar Children Series was created by Gertrude Chandler Warner, a teacher, when she realized that there were few, if any, books for children that were both easy and fun to read. She drew on her own experiences in writing the mysteries. As a child, she had spent hours watching trains near her home, and often dreamed about what it would be like to live in a caboose or freight car. In each story, she chose a special setting and introduced unpredictable, unusual or eccentric characters, to help highlight the Aldens’ independence and resourcefulness. Miss Warner lived in Putnam, Massachusetts until her death in 1979.