Get ready for a splish-splashing, action-packed tale in the bestselling series for young readers who like mermaids, monsters and princesses who are always ready for adventure! The Princess in Black and her friends are enjoying a day of sun and sea on Princess Sneezewort's royal boat when a real, live mermaid princess emerges from the waves! Can the masked heroes help her learn that being a princess means more than just being nice - it means speaking up?