Kim finds out she had a great aunt Miriam - aka Mim - who was shamed out of town because she was implicated in a theft at the Middleton Exposition 100 years before. Mr. Barkin related the story of how his ancestor - Constable Barkin - pinned the crime of a stolen energy device from a Prof. Demenz on Mim. The reality was that Bartholomew Lipsky (Dr. Drakken's ancestor) and his assistant Ms. Go stole the device, but it was lost as Mim Possible was chasing them. Mim was unfortunately caught in a photo taken by a young cub reporter - Wade's great-grandfather - who is still alive. Kim and Ron visit him, and get his original photo plates. Wade enhances them and discovers the truth of who was the real thief, but also determines that the stolen device was activated during the chase, and will discharge a huge amount of energy within the day if not found. Kim and Ron go back to the exposition museum and find the device has been lost on top of an old taco stand all this time. Just as they find it, Drakken and Shego arrive to claim the device, as he's also been on the trail of his ancestor's life. As they grab it, Kim pulls Drakken and Shego off of their hovercar and let it escape. It then explodes, and Drakken and Shego realize the Kim has saved their lives.
—Tony-B4