"Freaky Fusion" is the tenth TV special produced for the Monster High cartoon series. The TV special ties into the Freaky Fusion - Hybrids, Freaky Fusion - Freaky Fusions, Freaky Fusion - Fusion-Inspired Ghouls, and Freaky Fusion - Save Frankie! lines.
The movie starts with the clip of Frankie being chased by Creature 4.0. Neighthan comes to her rescue by throwing a casketball ball into the air, but he sadly crashes into the Bite-Centennial board. Frankie helps him up, and he asks when they get back to the others if they can skip telling them that part. Creature 4.0 squishes the ball with Frankie's face on it, and Frankie runs with Neighthan. Sirena Von Boo distracts the creature with her iCoffin and takes a picture of him on her phone. Then Avea and Bonita Femur come over to help them, and, having wings, lift Neighthan off the ground and Frankie jumps onto him. The scene does something that's like taking a picture and Frankie says she knows what we're thinking and goes on about Neighthan. She tells us that maybe it's the scary creature, and either way, she's sparked our attention. She begins to talk about how this is about family, but realizes they need to start from the beginning and then remembers that it needs to start at the opening titles. So she presses a button and it goes.
After the opening titles, it shows the Bite-Centennial theme at Monster High, which is a really big deal. Mr. Where comes over in invisible form, Clawdeen smelling his nasty stench, which he clears his throat with a cough to let her know he heard her saying that his cologne smells "cheap". Clawdeen pretend-corrects herself, and talks about how he's their favorite invisible teacher and that he loves giving them A's. Cleo calls it "very smooth", and Mr. Where hands out the papers for lines for the reenactment play asking if they're ready. Frankie tells Mr. Where that they're bursting at the seams, and Mr. Where talks about how proud he is of the play. When he tells them not to be late and disappears off, Clawdeen turns around with all the girls, and tells them that the cologne smells worse than a zombie's gym bag. She tells Ghoulia no offense, and Clawdeen, Cleo, Frankie, Lagoona, Ghoulia, and Draculaura go off without her to their lockers. Clawdeen notices the new students and asks if there's something wrong with them. Lagoona tells her and the rest they're hybrid monsters. Cleo asks if they should have to make up their minds, to which Clawdeen remarks to that Cleo can't even make up her mind when she picks an outfit for school. The girls walk by them and Cleo comments that the hybrid students don't look very friendly, which Clawdeen comes back with to her that she doesn't look very friendly. Frankie looks at a cute zombie-unicorn boy, and trips and falls down. The boy comes to Frankie's rescue and Frankie introduces herself. Frankie tells him this is the part where he tells her his name. The only boy of the hybrid students gets nervous, and can't say his name, but a moth-skeleton girl tells Frankie his name, which is Neighthan, and a purple-skinned harpy-centaur girl tells him to come on. Frankie tells Neighthan that she thinks he and his hybrid friends are really going to like it at Monster High, which he says "Yeah, sure" to and the skeleton-moth girl tells him to come on again. Cleo then comments that she told them they didn't look very friendly, and Neighthan clumsily trips on the banner for the Bite-Centennial celebration. When he walks off her friends, Frankie sighs in a romantically swooned kind of way.
After that, Cleo is finishing giving her presentation of her genealogy project for a class assignment. She brings the point to who she claims in the most important in the De Nile family tree - her. Her servants carve her picture into the stone. She says her family has more pharaohs and queens than anyone else's, so she says she should win the project, though Mr. Rotter tells her it isn't a competition. It is Robecca's turn, and she gives her assignment on Hexiciah Steam. Robecca tells the class about her amazing father, Hexiciah and tells the class that he was a teacher at Monster High. Rotter goes on about being the professor's favorite student. Robecca explains how Professor Steam worked in the Catacombs, invented something every single day, and that one day, he invented her. Mr. Rotter reminds everyone about being his favorite student again, while whirling a pencil and dropping it. Robecca explains how her father went missing sometime after, so she's kept a time box thing ever since. She says that every time she looks at it, it reminds her how grateful she is that Hexiciah discovered the secret to creating life, to creating her. Rotter tells her it was very good, and brings out the next student to give her presentation - Frankie. She tells of how her grandfather was Victor Frankenstein and that he invented her father (unmentioned, but is the great famous Frankenstein's monster) and, unmentioned, also created Frankie's mother, the monster's bride. When Frankie says that's all she knows, Mr. Rotter asks "That's it?", but Frankie can only show the blueprints for making her and an empty photo album scrapbook. Rotter calls her completely unprepared and tells her to rewrite the assignment, leaving Frankie in tears. Next is Abbey, whose report is a tad long.
In the Creepateria, the ghouls are having lunch and Clawdeen is writing in her fashion-design book. Clawdeen asks to pass the dead-sea salt, which Robecca and Draculaura politely can't make up their minds which should get it for her. She, Clawdeen, gets it for herself angrily. Lagoona tells Frankie not to be sad about the whole scare-itage project thing with a bad grade, which Frankie tells her it's not that, but not knowing anything about her heritage. Jinafire asks Frankie if she can ask her parents, but Frankie explains about her father. Lagoona sips her soup, which is too cold and Jinafire heats it up for her. Lagoona unsure says it's much better, and Neighthan and his female friends come near their table. Frankie offers for them to sit with her and her friends, but the blue-haired harpy-centaur girl says it's unnecessary when Neighthan was going to accept. Robecca and her friends talk about looking for Hexiciah's journal in the Catacombs, and when they leave, Frankie is still smiling at Neighthan. When gone, Neighthan tells the blue-haired harpy-centaur ghoul that that those ghouls were nice and they could've sat with them, which the centaur-harpy girl tells him that he shouldn't be naïve, and that Monster High is just like all other schools, and that they'll be moving onto the next school within a few days. Neighthan says that's not true, but the moth girl who is also a skeleton agrees with her and says "Yeah, flaw. Not flaws. They don't know what it's like to have two. Right, Sirena?" The third girl, the mermaid-ghost girl whose name is Sirena, says she agrees with all of them, while building a model of Monster High out of food.
Meanwhile, outside of school, the girls are walking to something to help them get to the catacombs. They find it, and on that gravestone, Robecca pulls the gravestone's skeleton skull top, and it triggers the Catacombs elevator. When there, Toralei and Cleo are arguing, and soon, they are in the catacombs. After a long journey down the Catacombs, the girls find a part where it's so dark, Jinafire lights it up. Lagoona then swims down to drain the water out. They find themselves near a door which when Robecca opens it is a bottomless pit. Then Robecca says she doesn't understand, and when she opens it again, a wild animal dragon (not person-monster like Jinafire) bursts out fire and the ghouls quickly shut it. Ghoulia, being a supersmart girl like she is, puts down the time box and it activates something. They discover that the secret is "it's about time" and Robecca comments how that's so like her dad. The girls go inside and Robecca tells them not to touch anything, which makes the whole crowd look at Toralei. She tells them she's got it that she won't touch anything, and they ghouls look around. Cleo finds out that her headband is crooked in the reflection of something, which Toralei bothers her with. Robecca finds something about Victor, and Frankie is glad that she did, but it turns out that her grandfather went crazy. Toralei sneakily pulls something and a bunch of stuff happens. A blue light is embellished and it grabs all the girls into it. The girls reappear in another version of the room in the Catacombs. The ghouls go upstairs and realize Monster High is under construction. They find out that they're in 1814 and Frankie gets happy to meet her grandfather. They soon need to find Toralei before she causes any more destruction. Draculaura gets upset due to iCoffin reception being gone in this time period. She cries, and the girls go inside. They get a lot of stares because of their up-to-date fashion styles, and one monster tries to touch Cleo, which Cleo tells her it's a Ghostier original and that it's magnificent and tells her to move along. After, the ghouls are still looking for Toralei and she's somewhere stealing monsters' fashion wears. Frankie and Ghoulia are looking for Toralei, and Frankie notices a steamy doorway making its entrance up, and there appears, a robotic cyborg (half human, half robot), and Frankie recognizes him as Hexiciah Steam, Robecca's dad.
Frankie and Ghoulia sit down in the classroom, and they watch eagerly. It turns out, Mr. Rotter, as a student was lying about being his favorite and was actually Professor Steam's least favorite student. Meanwhile, a boy named Sparky comes up to the room for his scare-itage project. He says he doesn't have a scare-itage for being an orphan. He shows the class his project of his "family." Everyone laughs, because his family is unstable and has poor quality. Hexiciah tells him he is missing something, and he doesn't understand. Later on, Frankie meets up with Sparky and tells him how her grandfather found the secret to creating life. Frankie realizes she's said too much, and leaves, with Lagoona and Jinafire having already found Toralei. They leave to the catacombs, but not without being spied on first. The girls are ready to go back home to their time period, but it turns out Sparky followed them.
- In Volume 1's webisode "Totally Busted", Monster High was established to be 2000 years old. This was corroborated by "Talon Show". "Freaky Fusion" retcons this to the school being 200 years old.
- "Freaky Fusion" continues the storyline regarding Hexiciah Steam. He made his first animated appearance in "Frights, Camera, Action!", albeit as mostly a shadow, his full appearance finally debuting in this TV special.
- The memories the students have of Frankie refer to events in "Friday Night Frights" (Robecca), "Why Do Ghouls Fall in Love?" (Draculaura), "13 Wishes" (Gigi), and "Scaris: City of Frights" (Rochelle).
- The three students sitting in the highest row on the left are missing when Robecca stands up to do her presentation.
- Fawn is among the students waiting outside after Creature 4.0 chased them out.
- The DVD of "Freaky Fusion" contains three webisodes that likely are exclusive to the DVD until some months into 2015: "Inner Monster 1.0 ", "Inner Monster 2.0 ", and "Boys Fright Out".