Madame Medusa is the main antagonist of Disney's 1977 animated feature film, The Rescuers. She is the proprietor of a seedy pawn shop in New York City.
Prior to the film, Medusa discovers that the world's largest diamond named the Devil's Eye is buried deep underground in a pirate's cave in Devil's Bayou. Much to her disappointment, the cave entrance is much too narrow for her to fit through. Neither her incompetent henchman Mr. Snoops nor her two pet crocodiles Brutus and Nero can fit through it. It is then that she decides to return to New York, where her pawn shop is located, and captures the poor orphan Penny to fetch the diamond for her.
Three months later, Medusa finds that although Snoops has managed to force Penny down into the cave, he is unable to persuade her to search as she was too worried about drowning and her teddy bear getting wet. Moreover, he has caught the little girl sending out messages in bottles. Medusa, frustrated with Mr. Snoops' inability to manage a "little girl", takes the next flight back to Devil's Bayou to take charge herself.
Upon arriving, Medusa made things even more miserable for Penny, so much so that Penny attempted to run away numerous times, only to be caught by Medusa and her two faithful crocodiles every time. At this point, Medusa finally lost her patience with Penny and declared that no matter what, Penny would find the Devil's Eye, and would stay underground until she did so, regardless of the danger. Prior to their search, Bernard and Miss Bianca from the Rescue Aid Society in New York arrive to try to save Penny, but Medusa panics upon the sight of them and nearly blows them away with her shotgun. This fails, however, as the two mice escape and soon afterward meet Penny face-to-face.
She ultimately forces Penny down into the cave, holding her teddy bear hostage, and refusing to lift her back out until she has found and retrieved the diamond. Since the cave fills with water at each high tide, Penny was aware that Medusa's threat was a potentially lethal one. She was accompanied by Bernard and Miss Bianca and with their help, she found the Devil's Eye. Unfortunately, it was stuck in the skull of a dead pirate and they could not get it out, but Medusa refused to hoist Penny up until she retrieved it. With the tide rising and the waters splashing violently, Penny and the mice recovered the diamond by opening the skull with a sword and were lifted back to the surface just in time. Medusa immediately indulged in her newfound wealth, refusing to let Snoops so much as a look at it, despite his pleas that they were partners and wanted an equal share. The group made their way to the riverboat where Medusa planned her escape.
While Miss Bianca and Bernard called their swamp friends for help, Medusa held Penny and Snoops at gunpoint, intending to escape with the diamond herself, threatening to kill Penny and/or Snoops if they tried to follow her. However, the two mice literally trip Medusa up, allowing Penny to grab her teddy bear with the diamond inside and make a run for it. Medusa is then attacked by the swamp critters, and is forced to use her shotgun against all of them, only to soon have that option removed when her shotgun was plugged up and backfired when she tried to fire it again. Medusa and her crocodiles fought the animals slowing her down, but were easily overpowered, and was soon at the mercy of Mr. Snoops' fireworks after the animals set them off.
Penny fled in Medusa's swampmobile, but Medusa refused to give up and pursued Penny by water skiing. She nearly had Penny at one point, grabbing hold of the back of the seat on the swampmobile, only to get her hands soundly smacked by Ellie Mae, forcing her to let go in pain. She ran into her two crocodiles with her booted feet and whipped them with a rope to get them to move faster, much to their anger. However, the rope broke and Penny was able to escape and Medusa was sent flying into her riverboat, which was now sinking due to the fireworks display, crashing into one of the smokestacks and hanging on for dear life. Medusa watched in defeat as Penny and the animals escaped with the Devil's Eye, leaving her to face the hungry Brutus and Nero alone while Mr. Snoops, all tattered and torn, fled the scene, all the while laughing at Medusa's misfortune.
It is unknown if Medusa was able to escape Brutus and Nero although it's implied that she never escaped this time and was presumably killed by them.