A little tugboat shows how he can bring big ships into the harbor even though he is small.

Tough Tug is a brand-new boat. He likes to swirl and twirl and run and race. He wants everyone to see what he can do. But on his first tow job to Alaska, he finds out what being a tug really means and learns an important lesson in the rough seas. Based on a true incident in which an Alaskan tug cut loose its own barge to rush to the rescue of the foundering tug of another tugboat company.

From early in the morning until time to say, "Good night," Mighty Tug works in the busy harbor, guiding cargo ships, pulling barges, and helping with rescues.