Luigi'S Mansion 3

The Mario Bros. have been invited to The Last Resort, a luxurious, art deco and high-rise hotel nestled in a mountainside area, and decide to visit it for a vacation, accompanied by Princess Peach, Luigi's pet ghost dog Polterpup and a trio of Toads that serve as the former's entourage. After arriving and settling in, Luigi wakes up during the night to find the hotel transfigured to appear haunted and the others missing. He discovers that the hotel's ghostly owner, Hellen Gravely, lured the group there as part of a trap by King Boo, whom she had freed from Professor E. Gadd's custody after his recapture in the previous game. King Boo announces his plot to exact revenge on Luigi and his friends for his past defeats by imprisoning them in portraits, but Luigi narrowly escapes to the basement through a laundry chute. With the help of Polterpup, who also avoided capture, Luigi explores the basement and comes across E. Gadd's car in the underground garage and finds his latest Poltergust inside it. Using the device, Luigi follows Polterpup to the lobby and finds that the professor was also captured.

Searching the surrounding area, Luigi comes across E. Gadd's Dark-Light Device in a safe and uses it to free him. Setting up a portable laboratory in the garage, E. Gadd explains how he was also tricked into visiting The Last Resort and taken hostage by Hellen, who then plundered his latest ghost collection to staff the building. Believing that Luigi's friends are likely trapped on the upper floors, E. Gadd recommends that Luigi finds the elevator buttons for the upper floors that had been taken from the main elevator after he secures two from a ghost he had defeated earlier. While exploring the floors, each featuring a different theme to them, Luigi is supported further by some of E. Gadd's latest creations – the Virtual Boo communication device and Gooigi, an ectoplasmic doppelgänger of Luigi who serves as the professor's ghost-catching protégé. Left without any other choice, Luigi begins his search for the missing elevator buttons in order to visit each of The Last Resort's many floors.

Coming across and defeating a variety of different ghosts throughout the hotel, Luigi reclaims the elevator buttons and rescues the Toads from them, the former of whom are then kept in E. Gadd's lab for safety. Eventually, he reaches the top floor where he confronts a furious Hellen and manages to defeat before rescuing Mario. Luigi then follows him to the roof where they find Peach's portrait. Upon freeing her, the group is confronted by King Boo, having lost faith in Hellen and her staff earlier and prepares to imprison them and their allies in a single portrait. After being inadvertently saved by Polterpup at the last second, Luigi, aided by Gooigi, finds himself forced to defeat King Boo once again. During the battle, King Boo enlarges the portrait's frame in an attempt to pull in The Last Resort with Luigi still on the roof. Luigi then triumphs over King Boo and manages to recover the portrait moments before the whole hotel crumbles to the ground from its endured strain. After freeing his friends from the portrait, the ghosts Luigi had captured escape from their containment in E. Gadd's now-destroyed lab and attempt to attack, but they suddenly become social when the jewel from King Boo's crown vanishes, suggesting that they were all brainwashed. E. Gadd, seeing the ghosts upset over their home's unintended destruction, elects for the group to build a new hotel, while the recaptured King Boo is returned to his custody alongside Hellen. Depending on how much money Luigi collected throughout his adventure, the new hotel, which is built in E. Gadd's image, will be different in size. After the grand re-opening, Luigi and his friends return home.