在这部三条美人鱼冒险喜剧/家庭片中,艾蜜莉、赛琳娜与贾姬三个感情深厚的好姊妹，外表如同一般青春少女，实际上可都是能在海中遨游的人鱼。在一次认识海底生态的校外教学中，艾蜜莉无意间展现了能跟鱼沟通的能力，而引起坏人注意，夺取她们的DNA做研究，面临人鱼史上最大危机，女孩们有办法靠着勇气与决心化险为夷吗？
Emily, Selena and Jackie - known to their 50 thousand YouTube fans as The 3 Tails - finally bring their journey to the big screen. Their mermaid adventures have enchanted fans for more than five years, as the girls struggle to understand the meaning of their special gift, protecting their secret from the world. Even their parents don't know that they have the ability to transform into mermaids. In The 3 Tails: A Mermaid Adventure, their lives are threatened after a stranger learns of their abilities and kidnaps one of the girls in order to harness her DNA. During a perilous ocean rescue mission, they discover that mermaids are not the only endangered species in the sea.
