"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! Eeeeeee! Princess Posy needs their help protecting her very cute sea goats from being eaten by a very greedy kraken. But the princesses and the Goat Avenger quickly realize that fighting underwater can be tough for land dwellers, and only the mermaid Princess Posy can save the day....

Fourteen-year-old Doreen Green's work as a superhero leads to problems with her life in middle school, but when a new shopping mall creates turmoil between two towns, Squirrel Girl is on the case.