Sirius is the twenty-ninth episode of ''Ken 10'', and the first episode of its third season.
Alien Force has driven Vilgax and Vilgaxson from Earth, and vanquished the other Sons of Gax. However, they have very little time to settle down before a messanger of an alien cult arrives. Challenging Ken to a battle royale, he warns that his master, the ancient force known as Sirius, will soon return to conquer the universe...
2. Grey Matter