When a faulty pier is scheduled for demolition, can semi-mer Emily and her friends in both worlds work together to save their homes? This is another exciting mermaid adventure for young readers based on the New York Times best-selling series by Liz Kessler.

Semi-mer Emily and her friend Mandy can't wait for a fun day at the theme park on the pier. But when they get there, the gates are locked. It turns out the whole pier is to be taken down because one of the pillars is decaying. Not only would that mean the amusement park would be gone, but also Mandy's home and the place where Emily's family moors their houseboat would be removed--along with all the animals and plants that live under the pier.

Emily and Mandy know that to protect everybody above and below the water's surface, they need to fix the pier. Luckily, a sunken pirate ship and an underwater playground give Emily an idea, and with the help of mer friends Shona and Aaron, they come up with the perfect plan. Based on the New York Times best-selling series by Liz Kessler, this underwater adventure proves just how much these friends can achieve when their two worlds come together.