The Wallace brothers and Muyunda plan a quiet camping trip on Lake Kariba on the border between Zambia and Zimbabwe, but things turn a little hairy.While photographing hippos one night, Bruce sees a mysterious boat loaded with uniformed men and an assortment of weapons crossing the lake, and the boys decide to investigate.Their curiosity leads to both Bruce and Muyunda being captured by guerrilla fighters intent on overthrowing the Zimbabwean government. It is up to Nigel to rescue them which he does by setting fire to the surounding bush, nearly incinerating his brother and friend in the process!Together again, the three boys have to race against time to reach the immense Kariba Dam Wall before a bomb explodes set to bring the wall down.