In "Pastry Puff Panic", HIM was unable to break out of his coffin, so he sent out his Black Z Rays to bring rise a mummy from the dead. This evil mummy was known as Mummy Man. He lured Mummy Man down to the basement to break open the seals to his coffin but Mummy Man was too weak to open them. HIM told Mummy Man that instead, he had to venture out into the real work and seek a white light force to help him open the coffin.
Mummy Man went out into the city and came across a man who was just closing up his store. The man told him that unfortunately, he was closing and would not be able to help him. Mummy Man threw a rage and smashed up the entire store and attacked the people, screaming about a white light force. He would later move on to wreck a bunch of other buildings after that.
The next day, reports of Mummy Man's destruction were all over the news and The Mayor of New Townsville alerted The Powerpuff Girls about it. Professor Utonium deduced that the "White Light" that Mummy Man was talking about was in reference to the white energy auras being emitted by The Powerpuff Girls, which got him to worry for their safety.
Later that day, The Powerpuff Girls got into a fight with Mojo Jojo, when he tried to steal their pastry puffs. Buttercup kicked Mojo's butt and sent him flying over New Townsville. One of his pastries fell out of Mojo's pocket and landed in Mummy Man's mouth. Mummy Man enjoyed the taste of the pastry puff so much that he became dead set on finding more pastry puffs and he didn't care how much destruction he caused to find them.
Mummy Man went around town stealing pastry puffs and this caught the attention of The Mayor again. The Powerpuff Girls assumed that Mojo Jojo was behind the stealing of the pastry puffs and that Mummy Man was actually a robot mummy, created by Mojo Jojo. The Powerpuff Girls tormented Mojo because of this but they were embarrassed to find out that he was actually not responsible for the stealing of the pastry puffs.
Just then, The Powerpuff Girls spotted the real Mummy Man stealing pastries from a pastry stand and they got into a fight with him. Mummy Man used his bandages to steal their powers, having detected the white light from them, rendering them powerless. Mojo Jojo even came in and tried to stop Mummy Man but Mummy Man grew super huge and smashed him in one stomp.
Poochie donated his white light to The Powerpuff Girls, giving them the ability to fight Mummy Man again. Mojo Jojo landed a second attack on Mummy Man, knocking him dizzy for just long enough for The Powerpuff Girls escape from his grasp and destroy him.
Although The Powerpuff Girls may have destroyed Mummy Man, one of his bandages still contained some of the white light and it flew away, unharmed. It flew back to the haunted house where HIM was and landed on his coffin, unlocking the seals and setting him free. This was only the beginning of HIM's ultimate plan.