It's summer, and Tess would like nothing better than to spend one lazy day after another with her best friend, Candice. But Tess's mother Sue believes that Tess is old enough to work alonside her on her fish boat, the Henry Bay.
On their journey up the sometimes terrifying B.C. coastline, the most reluctant of deckhands becomes a skillful crew member and learns how to take responsibility for herself and her new cat, Maa-mou. Sighting dolphins, having a breathtaking brush with orcas, and visiting the deserted village of Memcwumless are all part of Tess's summer and lead to her greatest challenge: while her mother assists a boat in distress, Tess has to take the wheel of the Henry Bay.