Henry, Jessie, Violet, and Benny used to live alone in a boxcar. Now they have a home with their grandfather and a new computer to play games on! During a visit to a computer game company, the Aldens meet the designers of their favorite game: Ringmaster. When the designers learn the Aldens are Ringmaster experts, they ask for their help. Would the Aldens test the new version of the game before it is sent out to stores? The Aldens gladly agree. But soon, the characters in Ringmaster II are giving the Aldens strange clues about people and places in real life! Is someone using the computer game to tell them something is wrong? The Boxcar Children are determined to find out!