BD is back in a new adventure. Baseball season is over, so nine-year-old Marty Stevens (nicknamed BD by his friends) and his twin sister Marsha decide to go to summer camp. Marsha goes to Camp Culture on the north side of Lake Loon to learn to play musical instruments, dance and take pottery-making classes. Marty goes to Camp Walkalot on the south side of Lake Loon to go hiking and fishing. The two camps participate in an annual inter-camp competition between the sophisticated musicians and the tough outdoorsy campers. It is the classic battle of brains versus brawn. Who will come out on top? Marty’s friends Jake, Mumbles, Sticks and Trip join Marty and Marsha at camp to add to the fun–and accident–filled adventure.