Little Toot had never been to San Francisco. As he steamed under the Golden Gate Bridge and saw the sunlit bay filled with busy boats of all kinds and the high hills perched above the city, Little Toot knew he was going to have fun. And Little Toot did have fun until the San Francisco fog crept over the bay and engulfed the tiny tugboat. Little Toot was lost!

When the Mississippi river floods, adventure-loving Little Toot sets out on a daring rescue mission. The plucky little tugboat, with the help of several forlorn old steamboats, once again faces a challenge to his resourcefulness.