Meanwhile at Fresh Spaghetti Tubbie, Swagmaster and Chris notice that there is no more spaghetti coming out of the production line. Chris thinks Swag just shoved his head in there again, but Swag denies it, and stated the spaghetti machine must be broken. Chris realizes that the only way to get the machine working again is to go down and fix it, but Swag refuses to go because of a rumor of a mutated spaghetti living underground. Chris tells Swag that if that's the case, they need someone dumb enough to go down there as a sacrifice. Mario then appears outside and starts protesting for spaghetti, a perfect candidate for the job.
They let Mario in and lead him to the entrance of the basement, and Mario just jumps right through the hole without getting full instructions first. He lands in the basement, which no surprise looks exactly like the setting from Chapter 1 of BATIM. As he continues to search for the machine, Mario finds a cardboard Bendy and mistakenly calls him Mickey Mouse. He is about to continue his search, but he accidentally activates a projector which puts on an advertising of the spaghetti factory with Bendy. When the advertisement finishes, Mario gives an applause, but is shocked to see that the cardboard Bendy that was right behind him suddenly disappeared. He looks around and sees the cardboard cutout peak at him from a door and then run away.
Mario chases after the cardboard Bendy, but the cutout is way too fast. Mario comes to an intersection, and the cardboard Bendy starts peaking at him again from one of the directions. Every time he turns to look at him, Bendy would always hide behind the corner, so Mario uses this to an advantage and starts playing red light green light. Mario then cheats and starts saying red light and green light even faster, and the cardboard in rage, quits and explodes.
Mario celebrates his victory, and then all of the sudden realizes that he actually made it to the spaghetti machine itself. Mario attempts to turn the machine on by saying "Open sesame", which obviously fails. Just as he's about to leave however, Mario trips on a tape and turns it on in curiosity. The tape then gives Mario instructions to go and find a dog, KFC chicken, and old man to put on their pedestals in order to get the machine going. Mario has at that moment lost all hope due to the fact that none of those items are nearby. As he begins to leave again, the real Bendy comes through and door and starts doing a dance while chasing him.
Mario attempts to run away, but Bendy then climbs onto a shelf and knocks a bowling ball, fire hydrant, picture of the King from Zelda CDI, Master Sword, and a piano onto him. Mario gets crushed flat, but still manages to escape into another room and lock the door. As Mario attempts to hide and hope Bendy goes away, he trips on another tape which just spurts out random gibberish. He tries to get the tape to stop, but he is too late when Bendy breaks through the wall and continues to chase him.
Mario continues to run, and runs into the room with the corpse of Boris the wolf. Seeing the open chest, Mario uses an advantage and hides inside it while Bendy runs across the hall searching for him. As Mario is about to leave, Goofy comes by the room and sees the dead corpse thinking it's his dead mother. Goofy grabs the corpse mourning the loss of his mom, but Mario then jumps out of the corpse chest and scares Goofy. The sight of a literal chestburster shocks Goofy, and he dies from cardiac arrest. With Goofy dead, Mario gets the idea to use his corpse on the pedestal for the dog.
With more hope than before, Mario continues to walk through the basement searching for the items, and then comes upon the food storage room, we all know how Mario reacts when there's food nearby. Mario goes through the storage room, and looks into a crate hoping there's something he can eat. Instead, Bendy pops out of the crate scaring him, and Mario in fear, splashes a bucket of ink onto his face, turning Bendy into the Ink Demon. You might expect Bendy to start mercilessly murdering Mario by now, but instead, Bendy yells at Mario for getting ink all over the place and throws a bunch Minecraft chickens at Mario, which all beat him up. A few of the chickens get on the stove, and when Mario turns it on by crashing into it, the stove cooks them into KFC Chicken. Now with the 2nd piece of the puzzle complete, Mario places the bucket of chicken on it's pedestal. Mario celebrates his victory, but before he is able to go search for the final item: An old man, he is kidnapped by a shadowy figure.
After a few seconds of straight up darkness, Mario is then shown tied up to a chair. A mysterious figure known only on this wiki as ??? wakes Mario from his tied up prison, and reveals himself as a worker who has been trapped in the basement since 1920. ??? believes that the only way to leave this prison is to worship the Flying Spaghetti Monster (The same one from R64: The Spaghettipocalypse). Mario tries to tell him that there is a hole that leads to the surface, and he can easily get out, but ??? denies it and thinks Mario is just telling him lies. Mario gets angry at ??? for taunting him, and uses all his strength to jump while still in his rope prison and crush him. ??? then pulls out an axe, and attempts to kill Mario and sacrifice him to the Flying Spaghetti Monster. Mario continues to use him jumping ability to escape, and nearly does until he realizes the only way to get away is the nearby stairs. Now with nowhere to run, Mario decides to go out taunting him, and starts singing "Suck a di**" to ???.
Just as ??? is about to use all his rage and axe Mario in the face, a frying pan flies by and hits him in the face, knocking him out. The pan was apparently thrown by Bendy, who doesn't kill Mario, but instead helps free him from his tied up chair. Mario now sees that Bendy was never meant to be evil and only wanted someone to play with him. The two become friends, but just as everything seems fine, ??? wakes up and summons his Spaghetti Children mutants. Bendy runs up the stairs, and has to drag Mario due to the fact that Mario wanted to try and eat them. Mario tells Bendy that he can handle the mutants himself, and as the Spaghetti Children gain up on them, Mario devours every single one that comes near them.
About 30 minutes later, ??? is still summoning more Spaghetti Children to go and kill the duo, but as he uses up more and more of his time, he decides to go and check out the problem himself. He goes to the stairs, but sees that Mario ate almost all of his mutants, and was now extremely fat. Bendy uses this to an advantage, and pushes fat Mario down the stairs, crushing ??? and possibly killing him.
The duo use ???'s body as the 3rd item, and place him on the pedestal. Now with all the items in order, the two can now activate the spaghetti machine. Mario attempts to pull the lever, but it has been stuck in that position for a while, making it hard to use. When Mario finally pulls the lever, it breaks and gets stuck on FAST mode, causing millions of plates of spaghetti to be produced very fast. The overflowing spaghetti creates a spaghetti tsunami which starts carrying Mario through the basement. Bendy saves Mario by closing a door just as Mario was being carried in by the wave. Now with very limited time to escape, Mario finds the exit hole and tries to jump up to it, but with no use. Bendy now sees what he has to do, and he grabs Mario and throws him upward toward the exit. As Mario ascends back to the surface, Bendy waves goodbye to him, thanking him for playing with him as the spaghetti tsunami crushes and kills him.
Back on the surface, Swag is trying to use magic in order to make spaghetti come out of the processing line. The spaghetti tsunami flows a bunch of spaghetti through the processing line, so Swag thinks that his magic worked and that he is the "all powerful" spaghetti god. Mario makes it back upstairs, and notices the huge piles of spaghetti. When Mario attempts to get some, Swag refuses, saying that he did all the work and that the spaghetti is his. Mario, in rage from not getting a reward for his hard work, throws Swag into the basement entrance. Swag lands in the now spaghetti-covered basement, and starts vowing to get Mario when he escapes. ???, who was apparently still alive, encounters Swag, curious of who he was. Swag tells ??? to bow down to him, saying he is the Spaghetti God, and as we mentioned before about ??? worshiping the Flying Spaghetti Monster, ??? starts to fangirl as he has finally met his idle.