Twins Domingo and Carmen Rivera are ready for the big Camp Rivals Race, when the four camps compete in an annual cross-country running competition, but this year there are problems: in the boys' race there is a pile-up, and Andy, Domingo's old friend, manages to prevent him from winning--but when Andy sends a text warning Carmen to watch out in the girls' race the twins become convinced that some of the other kids are cheating by working together...

Teenage ATV riders Josh and Christyna find that someone has been sabotaging the trails, putting the safety of ATV racers and mountain bikers in jeopardy, and they need to find out who is responsible and catch the cheat before the next race.