When the Alden children accompany their grandfather to the Snow Haven Lodge, a series of odd occurrences threaten to disrupt the annual winter games.

It's a big week at Cogwheel Stadium-the baseball team the Clayton Cogs are playing for the pennant! The Aldens are helping out at the ballpark, and they're glad to be part of the excitement. But the other team's batters seem to know the pitches too well, and it's clear someone in the stadium is stealing the Cogs' pitcher's signals. Now the Boxcar children must find out who is spying for the other team!

The Aldens try to help a visiting Russian gymnast who is surrounded by mysterious people and events and who seems to have a secret.

The Aldens are excited to be playing in their summer soccer league, until someone begins sabotaging the teams.

The Alden children uncover a plot to sabotage the Greenfield Bears baseball team. Includes baseball puzzles and activities.