The Thornberrys are camping on the banks of the Amazon river so Nigel can perfect his insect repellent formula. Eliza becomes fascinated with a fresh water dolphin that she sees out in the river. Debbie is bored as usual when a teenage girl from the village wanders into camp. She and Debbie begin hanging together while Eliza worries that she could be a legend come true...a dolphin that takes the form of a young girl. Could Jao be a dolphin in human form?