Based on an original concept by the original author Akira Toriyama, the story, set shortly after the defeat of Majin Buu, pits Son Gokuu and his friends against a new, powerful enemy.

This special introduces four new characters: Abo and Kado red and blue aliens wearing battle fatigues similar to Frieza's army, one tiny yellow alien, and a young Saiyan child who vaguely resembles Vegeta named Tarble. Though very little about the plot has been revealed, Tarble has arrived on Earth, being pursued by Abo and Kado.

(Source: Wikipedia)