Team Phantom just sat in their English class. Valerie joined them not long ago, so her presence still felt awkward to them. She joined their group shortly before their summer break started. She simply figured Danny out and confronted Sam and Tucker about this. Danny just rolled with her as he was about to spend the summer break with a relative in Oregon. When he returned and the new school year started, Valerie was part of Team Phantom. Danny was relieved she and the others protected Amity Park in his absence.

Fall came closer, so were news of a day long field trip sponsored by the Mayor Vlad Masters. Danny can't but be skeptical of anything this man touches, even though this trip could just be something to push his image as the city's mayor. That skepticism got confirmed when said man – and Danny's parents – stepped into their class room, announcing a field trip into the ghost zone. Danny swears he saw in Vlad's eyes he had planned something.

As soon as school ended, Team Phantom made their way to Danny's house – his parents drove them – and they discussed what to do, because a class of teens in the ghost zone can't end well. As they prepared plan and packed equipment – like a few dozen wrist rays and what not – Tucker pointed out to his friends, "What about Walker? He wants you in prison and will consider just their presence in the zone as a crime!"

"Tucker is right.", agreed Sam. "But what if something blocks the portals?"

"Mm, I could ask around in the zone if one of them could block the portals. Shutting them down won't do much. Heck, can Vlad's even be shut down?", replied Danny. He opened a portal into the zone, a neat trick he learned over the summer he was gone, and flew in it.

After his portal closed, Sam sighed, "He still hadn't told us how and why he learned that."

"Yeah, in general, he didn't tell us much about his summer in Gravity Falls.", agreed Tucker.

Valerie asked, "And you take issue with that?"

"Of course! We normally tell each other everything!", said Sam annoyed. "Which makes it so weird that he hides something from us. I know he does!"

Danny flew though the green that makes up the ghost zone. He considered who to ask, who could block the portals, maybe even destroy Vlad's and would be willing to help him? He only can think of the Far Frozen, Pandora and a certain group of weirdos. He decided to ask the Far Frozen first, they could freeze the portals over, so that the Specter Speeder can't come through. Having decided on a plan, Danny shot to the Far Frozen sector... until Walker flew up in front of him.

"Walker! I have no time for you and your rules!", said Danny, annoyed as he felt he is on a time crunch. "What do you want? I am not even close to your prison!"

"What so annoyed? It seems like you don't want to see me right now, Phantom."., replied Walker.

"Listen, my idiot school class wants to take a field trip into the zone, I try to stop that from happening, because I know you would take issue with that.", explained Danny. "What was the rule? No humans in the ghost zone?"

"Exactly. Now you listen. I actually would allow then in case your plan doesn't work. But I demand something in exchange.", said Walker, giving Danny the reason why he is here. He wants something. "Ever heard of demons?"

Danny was surprised by that. He has. Demons are nasty. A different beast than even Pariah Dark, his future self and Vlad combined. "Yes, I have."

"Some of them found a way to get into the ghost zone. We – the Observers and I that is – have been looking for a way to get them out.", explained Walker. "They proposed that we give you a try. If you beat them, maybe make them stuck in their own realm, I will nullify your sentence."

"Have you asked anyone else?"

"No! Demons can take out ghosts like it is nothing!", said Walker in fear. "But you as a half human, they shouldn't be able to kick you out of existence by a bare touch."

Danny never realized how afraid ghosts can be. "Mm, okay. Any idea where these demons are?"

"Their leak is somewhere close to Princess Dorothea's kingdom.", informed him Walker. "Skulker, the other ghosts and I will leave you alone. We really don't want the demons in here."

"Understandable. Thanks."

Soon, his class found himself in the basement of Master's mansion. Team Phantom was not happy when Danny told them about the change of plans. Sam even more so when Danny said they – meaning her, Valerie and Tucker – leave out of the deal he has with Walker and the Observer's by proxy. In other words, Sam doesn't talk to Danny right now.

While Danny's parents gave his class and friends a crash course on light weaponry – they exempted Danny as Maddie and Jack figured he knows a thing or two by just being their son – Vlad dragged him to a separate room for a talk. The man asked to Danny's surprise, "Daniel, do you know anything about demons?"

"Yes, Vlad. I know about dream demons like Bill Cipher and Alcor the Dream Bender, Cipher's henchmaniacs like Pyronica, Eightball, Teeth, Xanthar, do you want a list? I know they make one sided deals, are experts with loop holes." He choose not to say that he knows how to summon one. Vlad is the last person he wants this info to reach.

Vlad just looked at him dumbfounded. "It is... worrisome that you know this stuff, Daniel.", he said worried, "You don't seem like someone to be able to handle demons."

"And you can or what?", answered Danny insulted – and annoyed that he had been called Daniel twice – so he countered, "I know a few spells to get them off my back." A golden sigil appeared on his left hand back. "Have to go, the trip starts soon." Danny returned to his class, who was getting into the speeder. He loves to bamboozle Vlad.

Vlad followed them shortly, not showing how confused and worried Danny made him.

In the zone, the 'experts' were as clueless as always, having no idea what the floating doors were for. Danny felt not like bothering them with the truth. An hour in, a classmate of his – Mikey – complained, "Who would have thought that a trip into the ghost zone is so boring!"

"By the Great Gatsby, Mr. Jennings, the trip just started!"

"An hour ago, Mr. Lancer.", replied Star Morgan, Paulina's best friend.

Vlad approached the adult Fentons, then they landed on a floating rock. Vlad said, "It seems to be save if we get a closer look, outside the bus."

Normally Danny would argue, but he and the ghosts have a deal, so it may be really save to get out. His parents and some from his class took pictures of the purple swirls floating in the green that is this realms sky. Then they heard the growling of an engine. Looking around, Danny and his friends spotted Johnny 13 and Kitty dashing around on Johnny's bike.

Apparently Kitty saw then and pointed their presence out to Johnny, who then changed direction to their rock. The heavy machine landed on their rock and the ghosts got off. Maddie and Jack weren't sure what to do – grab their weapons maybe – Maddie had her hand floating over her gun. Johnny and Kitty made a bee line to Danny, who just – for all his class could see – was massively unbothered by the two spooks. Johnny looked to the class and asked Danny, "Isn't that your school class, Danny?"

"Yeah, someone decided that a High School class should take a trip into the zone.", explained Danny nonchalantly. Maddie relaxed somewhat, albeit she was confused why her son was just talking casually to this ghost. His class just looked on dumbfounded, while his friends wondered if he stopped to care about his secret. "And before you ask if I worry about Walker, we have a deal that he won't leave us alone."

"Ah, right, the demon thing.", said Johnny. "I'm surprised he keeps his words."

"Johnny, if the Observer's say he has to, he will keep his words!", chimed Kitty in. "He may play by his own rules, but he respects the Observer's as the real authority."

Jack dared to approach the ghosts and asked, "Um, how do you know my son?"

Kitty replied, "Well, how do you think we do?"

"I would assume Danny-boy sneaked into the ghost zone with the old specter speeder.", guessed Jack.

"You're right.", lied Danny, rolling with that excuse.

Kitty looked afar and said, "Danny, Johnny, isn't that Ember?"

Turning around, they saw Ember flying though the zone. Danny didn't knew she could fly o fast. Ember landed on the rock and breathed strongly. While ghosts don't have the need for air, they have a need for the air borne ectoplasm energy, which can be acquired by breathing. Kitty ran up to her friend, worried as she hadn't seen Ember be so stressed in a long while.

The class was hyped to see Ember – remembering her as the flaming star she pretended to be – when she said, "Something really bad happened! Like really!"

"What is it, Ember?", asked Danny. He hadn't seen any ghost so stressed in a long time. Only the ghost king caused such a reaction. "Is it Pariah Dark?"

"Worse! Demons! A bunch of demons broke into the zone!", yelled Ember, her hair flaring up in fear.

"Where?"

"Near Princess Dorothea's kingdom!", said Ember. That jumped Kitty, Johnny and his shadow. Vlad also stiffened up hearing that. Ghosts flying nearby also noped away, going for the Fenton portal. Only Danny was relaxed, which irritated Vlad and confused Sam, Tucker and Valerie. Demons seem to be a no-go for ghosts – even Vlad is bothered – they are supposed to be worse than Pariah Dark, yet Danny is unbothered.

"Demons are real?", asked Sam, more excited than anything. As she won't speak to Danny, she had been silent on this trip so far.

"Yes... listen, if demons are here, you better leave.", confirmed Johnny. "Demons are the most dangerous thing to exist."

"I think we can handle them!", said Jack confidentially.

"You can't! You can't even handle ghosts like the Box Ghost!", yelled Johnny, "There is no way you can handle demons!"

"Let us handle them!", demanded Maddie. "Oh my, a new field of study! Demons!"

"Madeline, I don't think you should study them.", chimed Vlad in, "If even ghosts say you shouldn't..."

"If one handles the fricking demons... Danny, remember your deal with Walker?", inquired Kitty.

"Deal? With a ghost? Daniel?", asked Maddie.

Danny took a breath, hearing his full name. His parents only use it when they are angry. He just sighed and transformed into Danny Phantom. He ignored his classes reaction of awe and said, "I have a deal with the ghosts, namely the jail warden Walker, that I help with the demons. You may not like it, but you can't handle them. You go back to Amity Park, while I keep up my part of the deal."

Then Ember yelled, "Oh no, it followed me!" There came a demon made of hot pink flames and one eye. The demon was easily 6"5', maybe even more. Either way, they easily towered over most of them. Vlad took steps back and walked to Danny.

"How do you think could you fight a demon?!", he whisper-yelled. "That can't end well."

"See and learn, old man.", replied Danny and floated to the demon. He greeted her, "Hey, Pyronica!"

"Oh! Double Trouble! What are you doing here?", replied Pyronica with a female voice.

"Unlike you, I, a half ghost, am supposed to be here. In the ghost zone.", answered Danny. "Pyronica, please leave. Why are you even here?"

"No one wants to be stuck in the nightmare realm.", was all Pyronica said, crossing her flaming arms.

Danny sighed and then snipped. A sigil appeared over his hand. Pyronica took a step away on the stone she stood on. Her eye on the sigil. "Ite procul! Somniis, daemon!" Pyronica was sucked into a demon, she circled around as if she was in a giant toilet and then vanished. "Demons never learn.", he muttered annoyed and flew back to the others.

"That was kinda anticlimactic.", said Paulina. Her friend Star agreed.

Sam was just even more angry. Danny never told them about this! Not that he can do magic – it looked like magic to her – nor that he seems to be in contact with demons! What else does he hide from them? She choose to speak, "Seriously? What else don't we know?"

"I have to agree with Sam. Since your trip to Gravity Falls you haven't told us much.", said Tucker. "Don't you think we should know about this demon trick of yours."

Before Danny could answer, Ember asked, "Do you have a more permanent solution for this Pyronica and other demons?"

"Actually yes.", answered Danny. "Wait here." He opened a portal. This portal was not like any ghost portal. Ember could feel the demonic aura of the portal. She froze when she saw Danny flying.

"Did he just..."

"Whatever that summer happened must have made Fentina more confident. Or idiotic.", muttered Dash.

"Or he appears more confident now that he doesn't need to hide his ghost side from you.", theorized Valerie. "Should we wait here or return to Amity Park?"

"I for my part go in there.", stated Sam and walked to the Portal. "I demand answers."

Tucker grabbed her arm, "But he said to wait here! Not to mention, this portal leads to a demon world!"

"Mr. Foley is right, we should not go in there.", chimed Vlad in. "At least not you children."

"I don't care! I need answers!", was all Sam said when she jumped in. Tucker sighed more annoyed than anything and followed them in.

Kitty looked unsure at the portal. "While Sam and Tuck tend to help Danny... these are demons!"

"Are we just gonna ignore that Danny knows a demoness like that?", stated Johnny perplexed. "If you go in there, Kitty and I won't follow you."

"Same.", agreed Ember. The three ghosts also left, irked out by the entrance to their worst enemies realm.

"I would say we bring the kids back and then follow Danny... assuming he isn't back by then.", proposed Maddie.

"I accompany you, Madeline.", offered Vlad, definitively not planning how to use the demons to off Jack.

But the class had a different plan. A plan that revealed itself when Dash just jumped in, followed by Kwan and then the rest of the class. Lancer then made his way to the portal. "We better accompany them. I hope Daniel has a way out." The other adults complied. If they can't stop them from going though the portal, they can at least keep an eye on them. "Teens in an unknown dimension can't end well." Lancer then sighed and said, "But who am I totell you."

Stepping though the portal, they found themselves in a corridor, with a massive golden open standing door at the end. The flour was black and white marble, the elegant and even for Vlad expensive looking carpet an intense purple. The walls were also fine stone, with pictures hanging. All these portraits showcasing what seems to be demons. Ten portraits hung, but two were covered by cloth.

The door itself was open, golden and they could see the class standing in it. Walking to the class, they looked at some pictures in passing. One demon looked rather human. He looked like Danny's phantom form, but with angelic wings, gold eyes and black blood veins. The clothes were hidden by a cloak. Lancer had a suspicion what this is about, but he choose to remain silent, partly because he was still surprised by himself that he dared to insult the Fenton's and the mayor.

Walking to the class, they saw what the teens were staring at. Danny was talking to a demonic figure. It was a very tall but thin figure, like Pyronica made from fire. But intense red instead of pink.

"Hezebah, now that this is decided, can you please punish Pyronica?", requested Danny.

"Of course, but you know you could.", answered Hezebah, sounding female.

"I know, but you're the queen of all fire demons.", countered Danny, "I only handle chaos demons."

"Mm, fair." Hezebah looked up. "Looks like your class jumped though the portal you left open."

Danny then saw them, too. "Ah, that's on me..." He walked to them. "Turn around, we're done here. Go back."

"But why leave already, Half'n'half? The fun just started!", said a body-less voice.

"Cipher?!", asked Hezebah, her body flaming in fury. "Show yourself!"

"If you wanna, Queen Hezebah." Bill Cipher appeared in his yellow glory, including black tie, top head and cane! His eye eyeing the class. "On the other hand, Half'n'half tends to be so protective."

Bill snapped and a portal appeared under the class, gravity did the rest. Danny flew after them. He saw Vlad turning invisible and how Valerie activated her Red Huntress suit. She captured some of the class, soon multiple students hung from her board like a chain that slowly descended to the ground. Danny then cloned himself, each copy capturing the rest. The real Danny caught Sam, then they all landed. One clone caught the adults, sans for Vlad who turned invisible.

They landed in a pine forest. When Danny checked if they all were okay – Sam still won't talk to him – Vlad showed up.

"Where the hell are we?", asked Dash frustrated.

"I can sense that we are in our dimension.", answered Danny.

A class mate of his added, "We seem to be in the US based on the wildlife I see. Red-breasted Sapsuckers!"

"And Western Withe Pines!", said her friend. "But why did he send us to Oregon?"

Then out of nowhere, Paulina starts to scream, pointing at a multi-headed bear walking by.

"Oh, I know why and exactly where we are!", said Danny relieved. "And hello, Multi-bear!"

The bear replied, "Hello Danny, why are you here?"

"Long story, Multi. But in short, Bill Cipher is back! Could you warn the others, especially the Zodiacs, while we go to the Mystery Shack?"

"Cipher's back? Will do, Danny!", he replied before running off.

"Follow me.", said Danny and lead the way.

His mother asked, "What was this bear and how do you know where we are?"

"Simple. Last summer, you send me to Great Uncle Stan, here in Gravity Falls.", explained Danny. "Multi-bear is one of the more, um, diverse figures of Gravity Falls. Relax, he is harmless."

"Oh, so we're going to Uncle Stan?", asked Jack.

"Exactly.", confirmed Danny. "Apropos... regarding Stan, something happened... how should I say..."

Suddenly a man in a trench coat riding an angered Unicorn jumped out of a bush. The Unicorn tried to throw him up but the guy kept on it. Danny whistled loudly and the Unicorn froze. The guy got off and then flipped the Unicorn by it's horn into the bushes. He then saw Danny and his class.

"Explanation, Danny.", he said.

"Nice to see you, too, Ford.", said Danny, rolling his eyes, "Do you want to tell mom and dad about the two Stans or should I?"

"If you tell me why you're here. Wait, is that your class?", asked Ford. "And isn't that Amitiy's mayor?"

"Yes. Long story. Long story short... I tell you in the shack.", said Danny. "Also, Cipher is back."

"He is back? Oh no! Then let's going."

As they arrived at the Mystery Shack, Jack had one burning question when he saw both Stans side by side. "How are there two of you?"

Stanford started, "You know how I have a dozen PhD's? Well, one of my inventions, a portal to the demon realm, backfired three decades ago. I was sucked into a different dimension. Stanley hijacked my identity, faking his own death."

"But he returned last summer! And we're still sorting the identity stuff out.", ended Stanley. "Mm, sorry for lying to you, Jack, Madeline..."

"Oh, you apologized! A rarity.", said Ford. "Now why are you all here in Gravity Falls?"

Danny then jumped into the story of the last few hours, nonchalantly about him being Phantom. Ford and Stan weren't surprised, so Maddie asked, "You know Danny is Phantom?"

The two Stans looked at each other. "Yeah."

Ford then said, "Now that this is said, Danny, we need to collect the zodiacs. Could you open your class a portal to Amity Park?"

"Sure!"

"Wait, does that mean you want Danny to stay here?", asked Maddie, "What is going on? What happened last summer?"

Danny sighed, so did Stan and Ford. Then they explained the last summer, namely what happened at the end, Weirdamagedon, Ford called it. Danny, the Stans and other people referred as Zodiacs fought the demon Bill Cipher. That the demon is supposed to be gone. Albeit Maddie had a feeling they didn't mention one thing. But the gist is, they have to battle Bill again, maybe live though a second 'Weirdamagedon' while they go back to Amity Park.

Then the entrance of the shop area of the shack opens, seven people walked in. The blonde girl, around Danny's age said in a panic, "We came as soon as Multi mentioned Cipher!"

"Good, Pacifica.", said Ford, "Danny, portal." Danny opened a portal to Illinois. Star saw though the portal their school. "Zodiacs! We will attempt the wheel. It should work now, that Stan and I fixed our issues."

"And if that backfires again?", asked a small kid in a blue suit.

"Gideon has a point.", muttered Pacifica. "It didn't exactly work last time."

Danny then sensed something. "Guys, we need to get out of here." As they walked out of the shack, they saw a rift forming. They saw Bill being punted though it by Queen Hezebah, the Hellfire Queen. She then closed the rift, leaving Bill behind in Gravity Falls.

"Of course, trap me here, Hezebah!", he complained. His attention then shifted to the Zodiacs. "I see, you want to try that again! Before you fail again, Danny, my offer is still standing!"

"Well, my answer is still no.", replied Danny unimpressed.

Vlad walked to Danny, "What is he taking about? What deal?"

"Oh, shut your trap, Vlad! You also asked him to be your apprentice as Plasmius!", called him Bill out. "Considering you're the weaker half ghost, I doubt you can teach him much."

"Y-You're a half ghost?", asked Maddie in shock.

Bill snapped his fingers, his magic forcing Vlad to transform.

"The Wisconsin ghost!", yelled Jack, recognizing Vlad's alter ego.

Then something comes though the portal Danny opens. None other than Pariah Dark emerges. Bill Cipher was not impressed and just snipped the king away into the forest. The class was impressed how nonchalant Bill was with the worst of the worst ghosts, while Vlad wondered if his half life ends today. This is why ghosts fear demons. Ghosts are nothing to demons.

Pariah Dark bounced back and attacked Danny, seemingly ignoring Bill, who was the one to hit him. Danny sighed and jumped into the air, turning into the demon lancer saw in the corridor, "Goin' Demon!", he yelled. Pariah stopped, he was as shocked as the others. If Bill wasn't just a Dorito with one eye,he would have smirked at this. Danny then shot Pariah with a yellow blast, ripping him out of existence, making him into nothing. Danny then flew back to the Zodiacs.

Sam eyed his demon form. She knew this is what he hid from them. As the realization why ghosts fear demons fully sunk, Vlad took a few steps away from Danny. Bill said, "Oh, you seem to have a grasp on these powers now, Danny!"

The zodiacs didn't answer, they just formed a circle, nuking Bill with ancient magic like they meant months ago.

Ford took a relieved breath, before asking, "What now?"

"Celebrating!", said his twin.

"My class and I return to Amity Park, I doubt they leave without me.", said Danny. "And I need to make sure they don't reveal my identity as Phantom. Or as part demon for that matter."

"We won't!", claimed Dash.

"Yeah!", agreed Kwan.

Mr. Lancer then said, "Theoretically, our trip won't end for another few hours, so we could celebrate your win, Mr. Fenton. I think we all need a break from this trip." His class celebrated hearing this.

"One last thing.", said Danny.

"What is it, sweetie?", asked Maddie.

Danny took a Fenton Thermos from Tucker and then sucked Vlad into it. "Plasmius is a menace, I couldn't let run him freely."

"I am pretty sure is fear of demons would have made him shut up.", said Sam.

"Oh, now you talk with me again?"

"I am still pissed you hadn't told me about this... but I guess I can forgive you.", said Sam.

Hours later, they returned to Amity Park. Vlad was send to a prison in the demon realm. This made Sam realize, "Wait, you're a demon king!"

"Yeah. When I beat Bill the first time, I kinda became his successor as the King of the chaos demons. Bill and his predecessor were the two covered portraits you saw in the corridor in Hezebah's castle.", informed them Danny. "Beating him was also why I got demon powers. Demons love rights by conquests."