Emily's looking forward to relaxing on a luxury cruise ship with her mom and her boyfriend Aaron - even if she and Aaron need to do some serious thinking about their relationship. Then they're overtaken by a pirate king and his two sons, who steal everyone's valuables. When the older son takes Aaron captive, Emily joins the younger son's crew to save him. But while living the pirate life and unraveling clues to the legendary Trident's Treasure, Emily bonds with the crew. Will she cast aside her mermaid life to join her new friends, or will she follow her own path?