When Cora reads a short story she wrote about a narwhal in her English class, Vivian Shimmermore mocks her and says that everyone knows that narwhals are fake. Suddenly Cora and her friends are embarking on an exciting quest to find these not-so-mythical creatures and prove Vivian wrong. And then, Cora finds out that their adventures could actually win her the top prize in the Ocean Writes contest... if she can manage to write the whole story down before the deadline!