cowboy-themed Big Horn Ranch. The opening of the book presents the Rover boys enjoying a winter afternoon with a snowball throwing contest at their military school, Colby Hall. The boys enthusiastically join in on the fun, but their good-natured mischief leads to trouble when one of their snowballs accidentally strikes their strict teacher, Professor Duke. This incident escalates into a series of humorous yet precarious events, causing the boys to be locked up as a punishment. As tensions rise and they await their punishment, the stage is set for their adventure that will involve mystery and camaraderie as they navigate life in a military academy and the challenges that come with it. (This is an automatically generated summary.)