Bentley: My paranormal scanner is maxing out on that structure.
Sly: A reading like that could only be coming off Mz. Ruby herself.
― When entering Mz. Ruby's lair[src]
Upon entering Mz. Ruby's lair, Bentley contacted Sly to tell him that his paranormal scanner is maxing on the skull temple in the distance. Sly assumed that Mz. Ruby herself was the source, which Bentley agreed with. Bentley concluded that Sly would have to find a way inside the temple if he wanted to confront Mz. Ruby.
After Sly slide his way down further into the lair, Mz. Ruby addressed her guards on the P.A system, demanding that they step up the production of the ghosts. She then revealed her plan to take over Mexico once they have all of the ghosts.
After getting enough treasure keys, Sly opened a locked gate, which allowed the Beast to enter into the facility and and break down the gate blocking entry to the other side. Once on the other side, Sly spotted a giant voodoo eggbeater, which was guarded by several water rats. Sly came up with a plan to unlock the cauldron's lid and thrash the production to build up enough steam pressure to get launched into Mz. Ruby's skull temple. To access the other areas, Sly had to sneak around the machine by Rail Walking in the shadows of the masks to avoid detection. After collecting enough keys, Sly unlocked the lid, which fell down and killed the guards. Once he hopped onto the lid, he was launched up to the skull temple.