In the series' sole two-part episode, "Blast to the Past", Sonic and Sally use the Time Stones to travel back in time, in an attempt to prevent Robotnik's planned takeover. They fail, but manage to get their younger selves to the safety of Knothole, with help from Sally's nanny Rosie Woodchuck. In the series finale, Robotnik builds the Doomsday Project to destroy the population. The Freedom Fighters launch a full scale attack against Robotnik, with Sonic and Sally destroying the Doomsday Project with the power of the Deep Power Stones. Robotnik is killed, and the Freedom Fighters declare victory, with Sonic and Sally kissing.