SMG4: Mario The Scam Artist is the fortieth episode of Season 8 and the four hundred and thirty-third overall to be uploaded by SMG4.
The real part of the video begins with Wario showing Shroomy his card which decided his fate. It was revealed that he has been given the Cory in the House card, to which Wario said that was a "bi-jillion years of bad luck". He then took this advantage by showing Shroomy his collection of good luck charms. These included but were not limited to: a whole "rabbit" (Who is actually a Demoman) instead of just its foot, and a live "lucky cat", which just died shortly afterward. Wario said that it could be all his for a low price of 1,000,000 coins. Shroomy hesitantly agreed; but as soon as Wario was about to take the money, a gnome appeared and Shroomy went off after it due to mistaking it for a leprechaun in hopes of good luck.
After that, Wario reminisced about the fact that it has been harder to scam people since Waluigi left. He looked at a part of a building's wall which looked like Waluigi, and a successful bank robbery which reminded him of the good old times. After this, he went on to call Waluigi a few names but was interrupted after hearing a cry for help from a nearby sewer maintenance building.
In the next scene, inside the building, it was revealed that the cry for help was coming from Mario, who was still trapped from the events of SMG4: Mario SAW. Mario continued crying for help until Wario walked in to discover him strapped to a chair. Mario heard Wario come in and begged for him to free him from the straps keeping him stuck. Wario momentarily pondered the possibility but eventually decided to rob Mario while he had the chance.
However, instead of finding money, all Wario found were plates of spaghetti. Mario naturally shouted at his greedy rival to stop, but Wario instead asked why he only had spaghetti in his pockets. After eventually deciding to stop, Wario asked Mario why he was trapped inside the sewer maintenance building and the red plumber gave a very simple synopsis of the events of Mario SAW, which made Wario uninterested before he realized that he has seen Waluigi recently. He tried hiding his excitement but failed, causing him to attempt to mask it as being curious. He then stated that he "just needs someone to help him with his scams", quickly realizing that he could make Mario a substitute for Waluigi. Wario then ran out of the building, coming back moments later with a tow truck to save Mario, hooked the tow cable up to Mario's chair and proceeded to drive like a madman to a nearby parking lot, landing on top of a car that was locked mere moments before landing. The two then left to go scam people out of their money.
For their first scam together, Wario and Mario found Fishy Boopkins sitting on a bench while talking to his waifu body pillow Hatsune Miku. Wario then came in and lied to Boopkins that he could make Miku come to life, so he did a short ritual, and then tossed the waifu pillow onto a roof. He then ordered Mario to do his part, and the red plumber emerged from the roof dressed as Miku. Completely fooled, Boopkins attempted to kiss Mario, much to the plumber's disgust and he was forced to kick Boopkins in the face. Realizing "Miku" did not like him, Boopkins left, much to Wario's anger.
For their second scam together, the duo found Wheelchair Koopa. Wario posed as a magician putting up a show, where he ordered the Koopa to close his eyes for the magic in making his wheelchair disappear to work. While he had the chance, Wario quickly threw the wheelchair over to Mario, who held a magnet for easier capturing but instead knocked Mario out, causing him to fall onto the street. That also led the wheelchair to be destroyed. Oblivious to what was really happening, the Koopa opened his eyes to see that the magic really worked. Just as Wario wanted payment, Wheelchair Koopa wanted his wheelchair back, causing Wario to begrudgingly agree to.
Realizing he had to quickly get back the wheelchair, Mario quickly fixed it up and sent it back. Wario, panicking that the Koopa would see through the scam, quickly made a false signal before running for it, although the Koopa believed all of that was part of the show. Once he and Mario were far away from the Koopa, Wario warned Mario that if he screwed up one more time, Mario would be cuffed back to the chair. Not wanting to let that happen to him, Mario agreed.
For the third and final scam, the duo found Luigi screaming while floating in sewer water calling for help. Shocked, Mario knocked out a nearby man selling fish, tied a rope to his body, and ordered Luigi to grab on. Listening to his brother's command, Luigi grabbed the rope and was pulled up by Mario using all his strength. Wario noticed Mario's effort to save his brother, and came over dressed as a nurse, offering to tend to his wounds. Although Luigi assured he was just tired, Wario ignored that and started repeatedly shocking him, setting him on fire, and extinguishing him. Wario then charged Luigi 30,000 coins for his service, but after Luigi revealed he had no money, Wario angrily tried throwing him back into the water and leaving him for dead.
Having enough of his rival's attitude when he saw how he was treating his brother, Mario kicked Wario aside and claimed he was no better than Waluigi. Wario threatened to fight Mario, finding it ridiculous that he would fight just to protect his brother. Just as Wario finished his sentence, he saw Mario and Luigi together protecting each other like brothers, reminding him of the fact that he lost Waluigi. Regretting what he did, Wario, depressed, headed back home.
When Wario got home, angry about having easily lost to the Mario Bros, started eating chicken. As he was about to bite into a wing, the food reminded him about how he said how he would never give his brother any of it no matter how much he asked. Refusing to believe he cared about Waluigi, Wario kicked the chicken bucket away. However, as the chicken bucket rolled away, he noticed it bump into his brother's old cap lying near him. Wario picked up the cap and started reminiscing all the fun times and scams he and his brother had together between 2017 and 2018. Completely depressed, Wario started crying and huddling his brother's cap around him.
Meanwhile, Mario saw on TV that Bob Bobowski had just opened a carnival. Excited, he asked Luigi if he wanted to come. Luigi, however, was too busy taking a bath to remove the sewer smell off him. Annoyed by what he said, Mario decided to head to the carnival himself. Later, Wario prepared to set out on a journey, looking up at the stars, promising to bring Waluigi home.