The Mystery in the Cave #50 -Boxcar Children

The four Aldens are rock hunting in Dragon’s Mouth Cavern, until Benny finds a sinkhole that leads to underground caves. While exploring the caves they realize that someone doesn’t want them there. But why? Can they solve this new mystery?
Dragon’s Mouth Cavern seems like an ideal spot for the Boxcar children to hunt for rocks and crystals. But when the children explore a cave, they also encounter some suspicious and unfriendly people who don’t want them there.