SMG4: Mario VS Siren Head is the twenty-first episode of Season 10 and the five hundred and seventy-fifth overall to be uploaded by SMG4.
This episode was aired on June 6th, 2020.
Mario meets a funny looking boi in the forest.
The episode starts off in a forest, with Mario and Luigi becoming lost as a result of an event which leads them to try to find their way home. As Luigi went on to investigate something in the bushes, it was the last that Mario ever found him.
Hearing his brother's screams, Mario sets out to find him and encountered many forest creatures on his way, including a tax consultant pug, a baby peanut, and The Globglogabgalab who tried to eat him. As Mario ran away from them, he was then shocked by the appearance of the Siren Head, and then ran away. As Mario hid by climbing up a tree, the Siren Head managed to get him down with his distractions. As the Siren Head tried to eat him, Mario screamed that it managed to convince the creature that he was scared. Later, he discovered that he could communicate with the Siren Head via screaming.
It was decided that Mario would bring him back to fit in with society, seeing himself to be a social pariah, evidenced in the fact that he had been abandoned in the woods for a long time.
First, he worked as a typical office worker but was quickly fired after he screamed which caused many workers to go off schedule, implying that they heard the end bell, for in fact he got angry as his computer crashed.
Next, he worked as an elevator operator, but that too failed due to scaring away Fishy Boopkins.
He finally got a job with the Rockford Fire Department, whose members Chris and Swagmaster are part of. Responding to an apartment fire in Rockford City, he managed to put out the fire easily by just spitting water from its mouth. Swagmaster praised him for his efforts, in which unbeknownst to him, decided to form a team that he calls the Woomy Fire Brigade, saddening an off-duty Meggy nearby, while Shroomy spots the creature while briefly showing his demon hunter side.
Now with a job, it is decided that it is time to find him a girl, with Mario trying his best to make him look good for the day. However, his poor fashion skills led to others staring at the Siren Head in shock and fear and even making a girl's head explode when he tried to say something when she complimented his looks.
Almost giving up, he then spotted a taco van with a siren owned by Waluigi, who was seen to be doing better than his brother after being released from prison the episode prior. Attracted to the van's sirens, he approached it, while accidentally scaring away Waluigi and the patrons. Having nothing else to say after he complimented it, with the van saying not even a single word, he walked away sadly, but became angered when Bob came close to it, enjoying the unattended tacos, making him break his spine. Fearing for its life, the van finally responded with a blush. Seeing the van happy, the Siren Head decided to sing a song so happily that it caused massive destruction all across Aubergine, including making SMG4's head explode.
Now finally together, the Siren Head and the van went off and coughed out Luigi, who was reduced to a mere skeleton, as Mario wondered about his whereabouts. Finally finding his brother, the episode ended with Mario saying "Oh, you!" complete with a title card featuring the brothers.