Notes: this is a short slice-of-life piece that was inspired by today's Inktober prompt ("ghost") as well as the official explanation for why Luigi was absent from Mario Kart Tour all these days—that, apparently, he'd lost his keys. This piece also serves as a prelude to Luigi's Mansion 3.

The title, "La Gazza Ladra" is borrowed from an Italian opera of the same name, meaning "The Thieving Magpie."

Mario was used to his brother keeping things neat and in perfect order. Needless to say, it was a surprise to Mario when, upon returning to their Brooklyn plumbing business with Peach, Daisy, Yoshi, Toad, Toadette, and Pauline all in tow, they all stopped to see the place in total disarray, with Luigi running around frantically looking for something. Luigi's ghost dog, Polterpup, watched curiously from the couch in front of the TV, amused at all of the things Luigi was throwing around.

"Oh my…" Peach whispered.

"If I didn't know any better, I'd say it looked like Link used Revali's Gale in here," Daisy commented.

"Hey, Bro!" Mario called. "What's wrong?"

Luigi looked up at him with a helpless shrug.

"I can't find my keys!"

Mario silently indicated the keyring hanging from a coathook near the front door.

"No, not those keys!" Luigi said. "The keys to my kart—they're gone!"

"…Well, that's a problem," Pauline said, flinching in sympathy.

Indeed, the entire reason that they were in New York was to run some of their semi-legendary kart races with some new scenery. Bowser and his brood were also in the city, with Rosalina making sure they didn't try anything; the turtles' presence in the city went largely ignored, much to the befuddlement of the Koopa King, who now began to realize why Mario hadn't questioned Bowser's appearance after he and Luigi fell through the warp zone from Brooklyn all those years ago—New Yorkers, it seemed, could see a lot without getting phased, no matter how strange it was.

But it didn't help Luigi's predicament, however, if he couldn't find his keys.

"We were just about to head to the courses, too," Toad sighed.

"Well…" Luigi said, scratching his head in befuddlement. "Don't let me stop you guys from enjoying yourselves. You go on ahead and start without me; I'll join you once I find my keys."

"We don't mind waiting, but if you're sure, we'll go," Toadette said. "If you don't catch up with us here, just remember—we're taking a warp pipe back to the Mushroom Kingdom and transferring on another warp pipe to Tokyo afterwards."

"I'll remember," Luigi said.

Toad and Toadette left, followed by a reluctant Yoshi; Pauline quickly realized that they had no way of navigating without getting lost, and she hastily chased after them to make sure they went the right way.

"We'll help you look for a while, Bro," Mario offered.

"But the race—"

"We don't mind, Luigi," Peach assured him.

"So we miss Bowser's opening speech about how he's going to beat us all and then gloat about it," Daisy scoffed. "Not a big loss."

Luigi conceded that she had a point.

Despite the place being small, there seemed to be several nooks and crannies to search. Polterpup soon moved from his position on the couch, heading over to the mini-kitchen. He sniffed around, and then picked up several metal spoons and forks in his mouth and began to prance around the place, hiding the silverware.

The others, too absorbed in looking for the keys, failed to notice—at least they did until Polterpup crossed in front of them and they saw him place one of the spoons into a nearby mousehole.

They then watched as he took the last remaining fork and returned to the couch, slipping the utensil between the couch cushions and then sitting back on it with a satisfied smile.

"…Did you see what I just saw…?" Mario asked.

"If it's the same thing that I saw, then it's clear to me what happened to Luigi's kart keys…" Peach noted.

The four exchanged glances with each other, and the ghost dog soon found himself surrounded by people trying to cajole him into revealing his hiding places. Peach finally made progress by bribing Polterpup with a piece of cake, and he gleefully led them all around the place, revealing all sorts of missing metal items—the silverware, a pair of pliers, some pipe joints, and even jewelry—

"Hey, so that's where Mama's brooch went!" Luigi exclaimed.

"Looks like it, Bro—and since Polterpup is your dog, you get to tell her about it."

"Wha-!?"

"But we still haven't found Luigi's keys," Daisy said, disappointed.

"They've gotta be here somewhere, I just need to keep convincing Poltertpup to lead me to them," Luigi said. "You guys go on ahead; I'll catch up as soon as I find them."

"Are you really sure, Luigi?" Peach asked.

"Yeah, I'm sure," Luigi assured her. "There's no point in you guys missing the race."

"Well, okay, but if you need help, just let us know," Mario insisted.

"Of course, Big Bro."

Mario nodded and glanced back at Polterpup.

"La gazza ladra," he chided, shaking his head. "We'll have to keep track of anything shiny from now on…"

As if to prove his point, Polterpup now snatched a gold-edged envelope from the coffee table. Luigi yelped and quickly retrieved it.

"Luigi, what is that?" Peach asked. "It looks like some sort of invitation."

"It is," Luigi said. "This was delivered back at the Mushroom Kingdom, but I brought it with me to think about—it's an all-expenses paid stay at some hotel called The Last Resort." He sighed. "I hadn't really planned on a hotel stay, especially since we'll be touring around here, but it is tempting. And it's been a while since my balloon trip to all those different kingdoms…"

"Sounds like fun; I'd have gone in a heartbeat, but I gotta head back to Sarasaland after our kart tour since I need to officiate some international meetings," Daisy sighed.

Peach flinched; she knew all about that.

"Well, Mario and I don't have anything to do after this," she said. "We could come along, if you wanted."

"Oh, yeah!" Mario exclaimed. "Would be nice to kick back and relax at a resort! I think you should take the trip, Bro!"

"Yeah, and who knows, if I finish my business up sooner than expected, I can join you guys there!" Daisy added.

"Okay, we'll go after the tour!" Luigi said. He sighed, looking back at the mess. "Now if I can just convince Polterpup to show me where he hid my keys…"

Mario gave his brother a sympathetic look before heading out with the princesses, watching him try to bribe Polterpup with a cookie.

Well, when considering all of the problems they usually faced, this was, thankfully, on the low end of the scale.

They could be grateful for that, at least.