The Growling Bear Mystery: When the Aldens visit Yellowstone they discover a map showing the way to an old cabin where gold is supposedly hidden, but they encounter lots of interference in their attempts to hike the trail. The Mystery of the Lake Monster: While visiting Lake Lucille in the Adirondack Mountains, the Aldens hear stories about a monster in the lake and then encounter evidence that it may be real. The Mystery at Peacock Hall: At the request of their distant relative Althea, the Boxcar Children arrive at her old Virginia mansion and investigate the mysterious incidents happening there.