The Aldens are spending a week at Camp Seagull on beautiful Claw Island. But as soon as camp begins, they realize that someone is not playing fair. Everything begins to go wrong for the Aldens—they lose their luggage, Henry misplaces the camp flag, and the campers on the other team use one of Jessie's ideas to score points for themselves. Are some campers so desperate to win the Olympics that they are willing to cheat? The Boxcar Children are determined to solve the mystery before the competition is ruined for everyone!