During this long last episode of Roverandom, we get to join Rover on his trip away from the moon and into the Deep Blue Sea, where he meets the merfolk and their surprising leader, Artaxerxes. Due to an accident with a dangerous serpent, Rover and Artaxerxes leave the ocean, and end up back on land. Finally, Rover is turned back into a regular dog and has some wonderful tales marked in his life.