It's a lovely spring day when Mama and Papa Poss hear a special broadcast on the radio: Johnny Splash, country music's star beaver, is launching a contest! Whoever writes the best love song by midnight tomorrow will get to record a duet with the beaver himself. Would Mama and Papa Poss be able to make it to Nashville, the birthplace of country music, in time? After ruling out trains, planes, boats, and even golden horned rhinos, they eventually hitch a ride with a mare named Lucille. The narrated story is followed by the songs "Lucille" and "The Girl I Left in Sunny Tennessee." "Heading to Nashville on Horseback!" is the fourth story in the "We're a Possum Family Band" series, which follows Mama and Papa Poss on their travels that bring them across North America to the birthplaces of Cajun, jazz, country, rock'n'roll, blues, and traditional Quebecois music.