Broncos score a TD to tie the game with ~30 seconds left, then the Chiefs run the ball instead of kneeling(!) and Charles was stripped, allowing Roby to pick it up and take it in for the score, and the win.
Also, kudos to Jim "Top Bantz" Nantz for zinging Charles (who was seen slamming his helmet on the sideline): "At least he held onto the helmet." Damn Jimmy, damn.