Lola is building her dream sandcastle--one with a tall, tall tower and sea glass that sends signals to mermaids. But the beach is crowded, and soon enough, a boy steps on her castle. Not to worry! Lola recruits him to build a wall. When a toddler with a bulldozer starts digging too close the walls, Lola decides he can be in charge of digging the moat. As the sandcastle grows, so does Lola's friendly group of helpers. There's only one thing that Lola doesn't want near the sandcastle: a wave! Will the new friends be able to salvage the mermaids' castle when their hard work is washed away?