In the lair, Mikey, and Raph and Mona are playing Frisbee while Leo was training. Yuuki was sitting down, reading silently. Donnie is in his lab. He didn't even notice Venus had walked in.
"What are you doing?" She asked.
"Research." Donnie briefly answered.
"Is there anything I can do to help?" Venus asked. She takes a paper off of his desk, only for Donnie to take it back and set it down.
"No. I got it. But thanks anyway." Donnie said not even looking up.
"Please, I want to help." Venus said.
"Then you can help me by going away. I can barely work with all of these distractions anyway." Donnie said as he was trying to ignore the playful loud yells of the Frisbee game going on and the training session.
"So that's all I am to you? An distraction?" Venus asked, hurt. But Donnie didn't hear her as he was still looking through the papers. "Fine, I will leave you to your work, Donatello. I'm sorry to bother you." Venus replied coldly. And She walked away leaving the olive green turtle alone to himself.
Donnie looked looked up to see that Venus had vanished and he looked around wondering where she had went. He went back into his work. Unbeknownst to the two of them, someone had been watching the whole thing the entire time, Yuuki.
Back to the Frisbee game with Raph and Mikey. "Coming at ya!" Mikey throws the Frisbee to Raph, but it goes too high and he misses. The disc flies towards Donnie.
"Yo Donnie, heads up!" Mikey calls out.
But he's too absorbed in his work to notice until it hits a stack of papers, sending them flying everywhere.
"Hey you guys!," Donnie yells out angrily as he grabs the disc "Can't you just leave me alone! I'm sick of all these interruptions! I can't work like this!" He throws the disc hard and Leo raises a hand, catching it in midair.
"Whoa, ease up, Donnie," Leo said. "You okay?"
"I know you ain't slept in day, bro?" Raph replied as they make their way towards him.
"Maybe, you're, I don't know, working too much," Mikey comments.
"I'm trying to find a cure for friends, trapped in the underground city," Donnie answered as he walks over to the computer with a crystal in his hand.
"That creepy place?" Mikey asked.
"Well, how do you think they feel? They're like prisoners down there." Donnie points out.
"Man, remember that spooky sole survivor guy?" Mikey answered.
"Remember what he said?" Donnie asked.
"As we speak, the power of the cavern's crystal moon is infusing your friends with its regenerative energy."
"I remember we had to put that wackbag on ice." Raph adds.
"And when our friends strayed too far from the crystal moon, they turn right back into monsters." Donnie continues. "We made them a promise, remember? A promise to find a cure, and I know the cure has something to do with these crystals, I just don't know what," Donnie begins to walk back into his lab, Raph was about to say something but Leo stops him.
"Let him go, Raph, Don's got that "no matter what it takes" look. We better just leave him alone."
Mikey and Yuuki give each other worried looks. As he walked away with his brothers Yuuki stayed behind. She walked up into his research lab.
"You know, you really hurt Venus' feelings. " She scolded.
Donnie looked up at her surprised "What do you mean?" He asked, confused.
Yuuki shakes her head "I'm not going to tell you. Your smart enough figure it out." She said.
it was in the middle of the night, as Donnie stayed up late working in his lab with the crystals. After trying a laser, he stops when he sees that it didn't do too much. He groans, taking off his goggles.
"I still don't have a clue what these things are made off," Donnie groans "Much less how they work,"
He yawns as his eyelids began to feel heavy then he was asleep on his desk.
Everything is dark at first and Donnie can hear someone calling out his name. He thought that it was Venus at first but it sounded a little different. He opened his eyes, he sees that he is back in the underground city. He blinks and he is now deeper into the city and he sees someone walking away from him as they call out his name again. When they turn around, he sees that it's Quarry in her human form.
He blinks again, he sees that she is back in her mutated form and she looks up at the Crystal Moon.
"Donatello,"
"Hear the crystal," Quarry tells him.
The Crystal Moon begins to melt and pour over the city and towards Quarry.
"Hear the crystal," A different voice calls out.
The liquid swallows Quarry in it, but she floats back out of it, she is reverted back into her human form.
"Donatello, hear the crystal," She tells him.
Donnie's eyes immediately opens and he shoots up from his chair. He turns to the crystals lying on the tray and takes them. "The crystal. Hear the crystal, that's it! At least I think that's it. I gotta wake the others. Hey guys!,"
Everyone is gathered around the lab table still half asleep after been woken up. "This better be good Donnie," Mikey groans sleepily and yawns. "A turtle does need his beauty sleep, you know."
"I've been doing some testing," Donnie said as he prepares a machine near the crystals. "The crystals react to sound, high frequency sonic disruption, to be precise," He turns the knob to start up the machine. "That will cause them to break down into their purest, simplest form." As the frequency of the machine goes higher the crystals begin glowing and start to hum louder. Then the two crystals suddenly melt.
"They liquefy!," Donnie said as he turns off the machine. "And in this liquid form, we can administer a version of it like a serum," He picks up the tray and pours the liquid into an tube. "A cure. Our friends will be able to leave the underground city forever."
"Don, I got to say," Leo starts with a smile.
"Way to go, egghead," Raph added.
"I, uh, I'm not so sure I deserve the credit." Donnie starts nervously "I kinda got the idea...in a dream."
"A dream?" Mikey questioned.
"Donnie, you've been working too hard." Raph said.
"No guys, don't you get it," Mikey spoke. "Don had a crystal dream like the one I had last time we went underground."
"We got to get back down there right way." Leo said as he walks over, picking up the tube.
"I've been working on that to," Donnie said as he opens a drawer from his desk and pulls out a blueprint. "It's a lot shorter, if we go straight down," They walk into Donnie's vehicle lab to see a giant vehicle. "Ladies and gentlemen, and Mikey," Donnie said as he presented the machine.
"I give you...the Turtle Tunneler!"
Donnie presses some buttons and starts it up. "Tunneler engaged."
Everyone gets strapped in except for Yuuki, Mona, and Venus.
"But, I didn't get the chance to build more seats into it." He said as he looks at the girls.
"That's okay I'll just sit here." Yuuki said as she takes a seat in Leo's lap. He blushes. He wraps his arms around her waist supporting her keeping her from falling off. Mona and Raph does the same as well. Donnie turns to Venus "You can sit with me if you want." He said.
" No, I'll stand thank you. " Venus answers not looking at him.
Donnie shrugs. "Okay, suit yourself."
"From here on in, the ride gets a whole lot bumpier." He warns. When Donnie starts up the drill and drives through the wall the whole vessel begins to shake violently. The shaking causes Venus to trip and fall over landing right into Donnie lap. She looks up and glares at him.
He smiles, nervously 'Hey, I tried to warn you."
She crosses her arms and looks away. "I'm not speaking to you."
The shaking stops when they drill all the way to the abandoned subway tunnel. Donnie drills through another wall.
The Tunneler drives some more deep underground. Donnie noticed that Venus has been quite for awhile now. Then he remembers what Yuuki had told him. He had hurt Venus somehow but what was it? Gears began to grind in his head but nothing came into his mind. He whispers quietly so the others can't hear.
"If I did something to upset you, I'm sorry." He said. "Can you tell me what I did? So I can fix it."
"Why should I? I thought that I was being inconvenience for you. "
"Inconvenience? When did I ever say that?" Donnie asked. He was confused.
"You said that I was an distraction and you never answered back when I asked why."
"Venus, sometimes when I get caught up in my work I do things or say things I don't mean. I'm sorry that I made you feel that way. You mean a lot to me. Please, forgive me."
"I-I have to think about it. " Venus said.
After some time, they have driven back to the underground city.
"Are we there yet?" Mikey asked and laughs a little, but Raph smacks him on his head.
"Ow!"
"Zip it, goofball." Raph groans.
They began to drive some more as it was a smooth ride the rest of the way.
"Next stop: underground city." Donnie said.
"Already?" Mikey whines. "I barely had time to watch the in-flight movie."
"Wait a minute," Leo speaks as he looks at the screen. "Isn't there supposed to be a light at the end of this tunnel?"
They are soon in the underground city, but they notice that it's dark. "The Crystal Moon! It's gone!"
"Okay, I know there was a giant Crystal Moon thing on the ceiling the last time we were here." Raph speaks.
"It can't just be gone." Leo said.
"It's worse than that," Donnie replied.
"What do you mean, Donatello?" Venus asked.
"The Crystal Moon was the only thing keeping our friends from turning back into monsters."
Donnie begins to drive again around the city, but they stop when they spot something on the screen. Everyone gasps when they see the rogue mutant.
"You were saying?" Mikey asked gravely and the mutant jumps onto the Tunneler.
The monster begins to pound on the machine and Donnie begins to drive, trying shake it off, but they don't get to far when they see a spider mutant in front of them. The monster shoots its webbing at them. Donnie starts up the drill, drilling the webbing off. The monster growls and hits the side of the machine.
"Hang on!" Donnie shouted.
He drills into the wall, knocking the monsters off the vehicle and into another tunnel. But as they make it through, they are suddenly attacked by two more monsters. They pick up the machine and began to carry it off, towards the edge of the cliff. Below them is a river of lava.
The monsters toss the machine, and it begins to descend as they fall down towards the lava. The turtles, Yuuki, Venus screamed as they came closer to the molten lava. Mona closes her eyes shut and clings to Raphael, wrapping her arms around him, hugging him tightly. The vehicle hits and sinks into the lava. Then, they burst out of the lava and drive to solid ground. Everyone is shocked, but relieved.
"Uh, shouldn't we be burnt to a crisp by now?" Yuuki asked.
"What?" Donnie asked when he sees their reaction. "You think I wouldn't design this thing to withstand lava? What kind of idiot do you think I am?"
"Are there different kinds?" Mikey questioned.
Donnie continues to drive the Tunneler into the city, and as they drive through, they see that it's deserted and very dark.
"Um, why are we traveling into the city and not to, say, Singapore?" Mikey asked.
"Because we made them a promise to help our friends, Mikey," Donnie reminds him. "And we're gonna to keep it." They drove in silence for a bit.
"They're out there," Raph speaks.
"Yeah, they're stalking us," Leo adds.
"Why don't they attack us already?" Raph asked.
"Cause they don't want the Tunneler," Mikey said gravely. "Just the chewy snacks inside!"
Donnie stops the machine in front of an entrance. "Guys, don't worry, I packed us a little something for emergencies," He presses a button and the top of the seats detaches itself. "Our seat backs detach to become tech pack units, high tech weapons, and survival gear. And by the looks of this place, we're gonna need them."
Donnie turns to Yuuki, Mona and Venus "It would probably be best if you stay close to us." He explained. "We don't know what's lurking out there."
"Excuse me," Mikey calls out as he was the last one to exit. "Why are we getting out of the nice, safe, heavily armored vehicle?"
"Cause I need to find more crystals," Donnie said.
"Don't worry, Mikey, it's gonna be a piece of cake," Raph reassures him, then they hear growling noises somewhere in the city.
"Yeah, except we're the cake!," Mikey exclaimed as they all rushed inside of the entrance.
Soon, they walk into a room where some people where frozen.
Raph walks up to the Entity "You still here? Yo buddy, that bus ain't coming,"
Donnie walks over and reaches for the crystal on the panel "The Entity's amulet seems to be the only crystal we've seen," The crystal begins to glow slightly. "It's a start, I guess, but I need more."
A noise is heard in the room and they look to see a door open all by itself. They walk in and see dozens of more people frozen in the room.
"What is this place?" Leo questioned as they look around.
"This is getting too creepy." Yuuki chimed in.
"Just what we need," Mikey said, nervously. "More creepy bald guys."
"Why do I get the feeling Mr. Sole Survivor didn't exactly tell us the whole story about his extinct race?" Donnie asked. A loud hiss is heard right near them.
"Heads up, guys," Raph said as they look towards the doorway and see a shadow coming their way. "We got company."
Donnie holds up the crystal and the door closes before the figure could make it. But it doesn't stop it from throwing itself at the door to get in. The turtles draw their weapons, including Yuuki while Venus and Mona get into a fighting stance. Suddenly the door begins to melt and they are surprised to see that it's Quarry that bursts through the door.
"Quarry," Mikey sighs in relief as they lower their weapons, except Yuuki who still held hers up. "Am I glad to see you!"
"Mikey, look out!" Yuuki shouted as she pushed him out of the way when Quarry shoots acid out from her mouth. It nearly misses them by an inch, and instead, melts the floor where Mikey once had stood. "Too bad the feeling ain't mutual." Raph murmurs. Quarry hisses as she advances towards them.
"What's up with her?" Raph questioned. "It's like she doesn't remember us at all."
"That's because I don't think she does." Leo said and Quarry hisses at them again.
"Raph!" Donnie calls out. "Your tech pack!"
Raph presses a button and the tech pack shoots out purple lasers just as Quarry was about to jump on them, sending her flying back.
"Don't worry," Donnie explained. "She's just stunned."
"Not for long!" Mikey exclaimed as she starts to stand up, to strike again.
"Keep her busy," Donnie said as he removes his pack. "I'm gonna try the antidote serum on her."
"Guys," Leo said. "Tech packs only."
Quarry charges at Mikey and he lets out a girly scream. He presses a button, shooting a net at her. It captures her for a moment but she uses her acid spit to break free. Mikey continues to shoot a barrage of nets at her until he eventually runs out.
"Nets, I'm all out of nuts!" Mikey said incorrectly and then corrects himself "I mean, nuts, I'm all out of nets!" He panicked.
"Relax goofball," Raph replied as he stands beside him and shoots a purple laser at Quarry then jumps on her. "Donnie, any day now with that cure thingy!" Donnie frantically tries to prepare the serum as the others continues to try and hold off Quarry. "Come on, come on." Quarry throws Raph off of her and rips the net open. Donnie pulls out the cure.
"Quarry, wait, it's me, Mikey!" Mikey said as Quarry approaches him. "Don't you know me?" Quarry stops and looks at him. "We're your friends, try to remember!" Quarry stares at him for a moment as if she remembers something then she turns feral again and picks Mikey up.
"Quarry, stop it!" Donnie shouted as he runs over to her and injects her with the serum. Quarry starts to wobble a bit before she drops Mikey and falls to the ground. The turtles immediately cover their eyes as she turns back into a human.
Quarry looks up at them "You came back, I knew you would."
"I can't thank you enough," Quarry finishes as she finishes dressing herself and walks to stand in front of the turtles, Yuuki, Venus and Mona. "You came back with a cure. It's unbelievable!"
"Our little Donnie's full of all kinds of ideas," Raph said.
"Quarry," Donnie speaks. "What happened to the-"
"My real name is Sydney."
"Oh, sorry. Sydney, what happened to the Crystal Moon?"
"The Crystal Moon, it's all our fault. We were getting stir crazy being trapped down here, so we tried to find a cure for ourselves. We used up a lot of the crystals, but it was hopeless. We thought perhaps a larger piece of crystal might work, so we turned to the Crystal Moon. With the help of some explosive geodes we discovered in a chamber in the underground city, we had hoped to break off a sizable piece of the moon. But the geodes were more powerful than we realized. The entire Crystal Moon fell from the cavern ceiling and sank beneath the molten lava. Without the moon's regenerative power, we instantly reverted back into monsters. Savage, mindless, fighting among ourselves, lashing out at everything that moved. But now that you've cured me, you can cure all of us, we can all go home!"
"Yeah, except for one little problem," Donnie said. "I only had enough crystals to make one vial of serum, never expected to find a shortage of crystals down here."
"With the Crystal moon gone, all the crystals are dead."
"We have to raise the Crystal Moon from the lava and bring back the energy source."
"What're you talking about?" Mikey questioned. "That thing must have melted away to nothing in that lava."
"Not necessarily. The crystals are almost indestructible. They don't liquefy from heat, they liquefy from sonic vibrations," Donnie explained.
"Well, if its down there, let's get it back up, where it can do some good." Leo said.
"Yeah, Donnie, you're on a roll, today," Raph replied. "Anymore bright ideas? We're gonna need one."
"Well we could try to use the crystal cable from the old underground tram, secure one end to tram tower and the other end around a large sturdy rock ledge, thus rigging a giant size variation of the old block and tackle. The ledge should provide us with a good angle for optimal leverage, then I'll take the Turtle Tunneler down into the lava to hook the cable to the Crystal Moon. We can use the explosive geodes Sydney discovered to dislodge the tram tower from it's location and topple it over. We'll be cutting it close, but it just might work."
"Just one question," Mikey calls out. "Who came up with this plan? Wackos-R-Us?"
"It is a little unorthodox, but it'll work...I hope." Donnie said.
They carry out the plan and Donnie and Sydney hopped into the Tunneler.
"Sydney, you don't have to do this." Donnie said as she closes the door.
"Yes, I do," Sydney argues. " The only one who knows where the Crystal Moon went down."
Donnie starts up the vehicle. "Let's do this quickly. I don't know long the heat shields will hold."
He drives into the lava and sinks it down to the bottom.
Back with the others, they are placing geodes around the tower.
"Explosives are in place," Leo informed
"Now all we got to do is sit back and wait for Donnie's signal," Raph said. Suddenly, they hear a roar and Leo turns on his spotlights, showing monsters are starting to surround them from above.
"Or we could keep busy by fighting for our lives!" Mikey exclaimed as the monsters jump down, closing in on them.
"Donnie, we got company up here." Leo calls.
"Stall them," Donnie said as they continued to drive. "But try not to hurt them."
"Hurt them?" Mikey questioned, and jumps out of the way when one of the monsters tries to attack him.
"Easier said than done." Yuuki retorted. A monster lunges at her and she quickly jumps out of the way. Venus jumps on top and and hits a pressure point. It falls to the ground unable to move.
"Remind me never to make you angry." Yuuki said.
Leo uses a grappling hook in the tech pack and is pulled out of the way when two monsters are coming from him. Mikey leads two monsters to a higher point in the city. "Come on you big uglies, follow the leader!"
Donnie and Sydney are still driving around beneath the lave until Sydney spots the Crystal Moon.
"We found it," She tells him.
"The Crystal Moon,"
"Good, keep an eye on the heat shields, they're starting to go," Donnie said.
Back on the surface, Leo is still using his grappling hook to evade the monsters while Raph uses the stun lasers on two bigger monsters. Mikey continues to run from the monsters behind him until he comes to an dead end. Leo drops in.
"Though you could use a lift, Mikey," Leo said as he pulls himself and Mikey out of the way just as the monsters attacks. Donnie and Sydney are now heading towards the Crystal Moon.
"Heat shields are down to fifty percent," Sydney informs as she starts to sweat from the heat. "Structural breach in two minutes, we have to pick up the pace!"
"Almost there!" Donnie said, sweating as well.
A monster approaches Raph and picks him up destroying his tech pack. Mona rushed over to help him. Another monster, slams Mikey against the wall.
"Donny, hurry!" Leo calls as he runs from two monsters. "I don't know how much longer we can keep this up!"
He picks up Yuuki and jumps off the ledge and presses the button that shoots out the grappling hook. He swings down to Mikey and Raph, Mona and Venus, kicking the rock monster before it got closer to them. "Coming through!"
"Guys, look out!" Leo shouted when he sees the spider monster crawling down the wall.
Before they could run, the spider monster shoots out its webbing and captures the six of them.
In the lava, Donnie is tying the cables around the Crystal Moon.
"Crystal Moon is nearly secure," Donnie said.
"Heat shield are almost gone," Sydney informs. "We've got thirty seconds before were cooked."
"I just have to lock off the cable!" Donnie tries to do that, but it misses.
"Him and his big ideas!" Mikey complains as they struggle against the restraints and the monster begin to close in on them. "Come on guys, let's go down to the underground city, we'll have some laughs, we'll get eaten!"
Back in the Turtle Tunneler, it's growing hotter and everything is sparking from heat overload.
"Heat shields are down to ten percent," Sydney groans. "We're not going to make it."
Determined, Donnie tries again to hook the cable. It finally latches itself.
"Yes! Guys, go now!"
"We're kinda tied up right now," Mikey retorted.
"If I could just reach my-" Leo cuts himself free. "We're on it!" He said as he cuts Mikey and Raph out of the webbing then turns to Yuuki and cuts her out. "Cutting it a little close, aren't you?" She asked.
Raph gets Venus and Mona out of the webbing as well.
Mikey uses his cable and makes it to the tower and setting off the explosives.
The tower falls and as it does, it pulls the cable with it and the Crystal Moon rises out of the lava, brightening up the cavern. And with the light, the regenerative energy turns the monsters back to the their human form. The turtles cheer.
"Don, you did it," Leo said. But there was no answer on the other end, "Don, Sydney, can you hear me?" Leo tries again, no response.
Venus felt her heart stopped. No it can't be. He can't be...
She immediately runs to the shore of the lava pit. The others following. There was nothing there. Venus shakes her head with disbelief. "No." She felt like she wanted to scream but she couldn't. Her heart felt like it was beginning to clamp up in a vice. He couldn't be gone. Her eyes began to tear up. She slumps to the ground and began to beat it frantically "Damn you, Donatello!" She wailed.
Yuuki runs over to her to comfort her.
"Uh, they didn't...they didn't make it." Mikey said sadly.
They hear a bubbling noise and they see the Turtle Tunneler bursting out of the lava. Everyone cheers in relief. Donnie, and Sydney soon step out.
They all rushed over to them. Donnie was met with arms being thrown around him as he was pulled into a tight hug.
He looked down to see Venus burying her face into his plastron. When she finally looked up, he saw tears beginning to flow down her cheeks.
"I didn't mean to make you cry. Please stop." He said nervously as he wipes the tears off from her .
"I forgive you! Don't ever do that to me again!" Venus cries. Donnie wraps his arms around her hugging her.
Donnie works on the serum and gives everyone the cure. And their all cured, they bring them back to the surface.
"This is it, guys," Donnie said as he helps Sydney out of the sewer. "Daylight again."
They all gasp in amazement at seeing the sunrise and Donnie sees Sydney crying a little. "What's wrong?"
"I...," Sydney starts as she continues to look up at the sky "I'd forgotten how beautiful it was. Thank you, from all of us, we owe you our lives."
They all walk away, relived to be free from the underground. Donnie waves at them.
"Come on," Leo said. "Let's go home." Donnie is the last one in and Mikey pops his head up
"Donnie, you may be a pain in the shell, but I'm proud that you're my bro."