Cover Page: Enel's Great Space Operations, Vol. 27: "For Avenging the Professor, Our Undying Gratitude".

Spacey (pulling his fellow Automata on a cart) approaches Enel and tearfully thanks him for defeating the Space Pirates.

Usopp starts the fight with Perona.

Unable to retrieve Usopp and Sanji, who fell when Oars crashed through part of the Mast Mansion, Luffy, Chopper, and Robin decide to press forward. Knowing those two would be fine despite what happened, the three Straw Hats hurried to find Moria. They head towards the giant freezer where the Warlord was last seen. Before they could get to the freezer; however, they go through the dance hall and encounter Hogback and Cindry.

Seeing the enemies before them, Luffy prepares to engage them. Chopper however tells Luffy to let him deal with Hogback and go ahead to Moria. Luffy obliges Chopper's request and with a little help from Robin, is able to pass by an attacking Cindry to the freezer. Having gotten Luffy through, Chopper confronts Hogback and expresses at how disappointed he is of his former role model. Hogback, upon recognizing Chopper after the reindeer transformed into his Brain Point, decides to confront him as well with plans to make the reindeer a zombie. As the two doctors confronts each other, the two zombies that Hogback asked from Moria, Inuppe and Jigoro, came forward to Hogback's aid. Meanwhile, Luffy reaches the freezer and confronts the lazily resting Moria.

Back at the bridge destroyed by Oars, Zoro, Usopp, Sanji, and Franky, prepares for what might be a fight with the giant zombie. The behemoth however instead of fighting, takes some debris and places it on his head due to its likeness to a pirate bicorne. With his new accessory, Oars continues on exploring the rest of Thriller Bark leaving the four Straw Hats unnoticed. Having been left alone, the four Straw Hats are relived. Usopp; however, is deeply scared of what had happened.

With the giant zombie gone, the four Straw Hats then face a new problem. Since the zombie destroyed the bridge, the gap is too far for them to jump over and the situation seems to force them to take another route, an option they do not have the luxury of taking at the moment. Fortunately, Franky is able to create a bridge across the gap from the debris around quickly. He however asks his crewmates to wait a few seconds later since he is not yet satisfied with the finish. With the bridge built by Franky, the four Straw Hats cross the gap and enter the Mast Mansion.

Upon entering the mansion, the four Straw Hats soon notice that they've entered a special room. Within it is the owner, Perona, waiting for them. From her, they learn that she, having eaten the Horo Horo no Mi, is the one controlling all of the ghosts on Thriller Bark. With that explanation, Perona wastes no time and sends some ghosts to immobilize the four Straw Hats. Unable to escape, all four of them were seemingly immobilized. Seeing her work done on the four, Perona set her Wild Zombies on them and decides to take care of the rest of the Straw Hats. However, just as she is about to leave, she suddenly notices that one of them was still standing and purifying her zombies. Thinking that she might had missed him, Perona sends another ghost towards the pirate, Usopp. To her surprise, Usopp did not fall down like the rest. Wondering why her powers aren't working on him, Perona asks what trick he was pulling. Usopp stated in response that he wasn't doing anything but told Perona why her powers weren't working on him. To Perona's shock, the reason that Usopp is not overcome by negativity was because he's already negative to begin with thus rendering him immune to Perona's powers altogether.

Unable to comprehend that such a negative person could exist, Perona tries in vain, along with her zombies, to cheer up Usopp. Usopp on the other hand, tells his fellow crew mates that he will take care of Perona himself since they could not. Relived by Usopp, the three Straw Hats moves on ahead to rescue Brook and Nami, leaving Usopp to deal with Perona. Unfortunately, Usopp did not intend for this. He wants them to stay and take out the surrounding zombies. Unable to get his fellow crew mates to stay, Usopp is left alone to face Perona and her Wild Zombies much to his fears and doubts.

Meanwhile, within the Thriller Bark church, Absalom's wedding is proceeding smoothly to his plans. The ceremony has gotten to the part where all that was left to do was to kiss the bride in order to fully consummate the marriage. With this, Absalom dangerously approaches a still sleeping Nami with his lips puckered.

Chapter Notes:
The title of the chapter is referring to Usopp's immunity to Perona's powers and is a reference to the live action movie Ghostbusters.
Perona ate the Horo Horo no Mi.