Summary

Madame Death was a 1940`s crimeboss that was offered by the Future Man to rule the world if she helped him. After several schemes that were thwarted by various members of the All-Winners Squad, they were finally met with the full force of the team aboard Future Man's ship. While Future Man attempted to send himself and Madame Death into the future to escape, Captain America managed to sabotage the ship's controls, causing Future Man and Madame Death to hurtle aimlessly into the past. 
Surprisingly, Madame Death returned to the present only a week later. It turned out however, that both she and Future Man had actually been lost in time for years, during which Future Man had perished from an ancient disease shortly after finally managing to fix his ship.  
Now back in the present, Madame Death used what remained of Future Man's technology to seek revenge for his death against the All-Winners Squad. She especially wanted to make Captain America suffer for having sabotaged the ship and consequently causing Future Man's death. Madame Death had also come to learn from Future Man that the current Captain America was actually Jeff Mace, who'd been chosen to replace Captain America after his supposed death towards the end of World War II. She therefore attacked New York City with what appeared to be reanimated American soldiers from past wars, as well as a reanimated Captain America who nearly managed to get Jeff to trade his life for him.   
The Human Torch luckily managed to discover Madame Death's ruse and destroyed the device that was responsible for the reanimated soldiers. Unfortunately, the device was coupled with a special heat-activated bomb and it exploded, nearly killing Miss America. She was luckily saved by Whizzer, but Madame Death as it turned out had been impaled by debris from her own device. Madame Death died contently however, stating that she would now join Future Man beyond life and time, where they could never be separated. 
 

Powers and Abilities

Madame Death was a successful crime boss with considerable resources and intellect. She was also an accomplished fighter. 
She later used what remained of Future Man's technology against the All-Winners Squad, primarily a cloaking device, a device that could generate what appeared to be reanimated soldiers, as well a heat-activated bomb. During her many years lost in the past with Future Man, she'd also come to learn much of future events such as how to operate his many devices and the fact that the original Captain America was actually presumed dead and had been replaced by Jeff Mace.