Autumn on the Maine coastline: beautiful red leaves, hot apple cider, crashing waves, and . . . dogs playing with porpoises? That's life for Lars and Bangor, a dog and harbor porpoise, best friends in the town of Ogunquit -- and everyone knows it. They became a sensation after Bangor was separated from his pod and trapped in the harbor, and it was up to Lars and his human, Natalie, to reunite him with his family.

Now, Bangor and his pod are back, but they're not the only newcomers in town: Oguinquit has been overrun with tourists and reporters (and in the off-season, too!) who want to catch a glimpse of the dog-and-porpoise duo. And to make things worse for Lars, a river otter named Marina has captured everyone's hearts -- including Bangor's! With Marina taking center stage, will Lars' and Bangor's friendship ever be the same again?