The Quantum Nexus is the tenth episode of the second series of The Sparticle Mystery. It was broadcast on February 22nd 2013.
Fizzy is inside the Quantum Nexus, which turns out to be industrialised much like the Sparticle Project, Ernesto and Fizzy go to stop the Sparticles while Reese and Holly go on ahead and Fizzy and Ernesto catch up with them and they realize its a furnace. The Sparticles have gotten inside with Tia determined to stop Fizzy and his team. Fizzy, Holly, Reese and Ernesto reach the computer room and they realize theres a company called the Quantum Nexus. Reese goes to the computer but Holly argues with her before Ernesto intervenes. Fizzy goes to destroy it but Ernesto stops him syaing this isnt the real Quantum Nexus. Sadiq, Tia, Liam and Frankie, they see a meteorite that has the Nexum being mined for energy and is the treasure Dreary said his parents always talked about. After walking for a while, they stumble upon Doomsday Dora who reveals the Quantum Nexus is supposed to solve the worlds energy problems but they're suspicious. Holly figures out Doomsday Dora works here. Doomsday Dora is meanwhile leading them around bu when Frankie speaks, she realizes its a child and changes images so she can help the children bring the adults back. She turns out to be a hologram, Holodora, who thinks she is Doras daughter.
Reese figures out that Dora is indeed a hologram as Ernesto finds security passes and they turn the security system on, causing Serena, Jeffrey and Callum who entered minutes ago to get detained by being transported to a room. Doomsday Dora is explaining how to get the adults back by leading them around and the Sparticles realize she thinks that she is her daughter. Holly, Ernesto and Fizzy are walking with the security cards when they come to a point where security cards are needed. Holly goes first and shows a security card and passes but gets transported to the security room before Ernesto or Fizzy can go ahead. At that moment, Serena throws a sword at the door to escape, nearly hitting Holly. Doomsday Dora tells them that the Nexium is melted and teleported through a wormhole to power the national grid on the other side. Holly, Jeffrey, Serena and Callum are walking under the furnace which is about to fire up in fifteen seconds but Serena falls so Holly goes back for her but it starts burning.
The Sparticles realize Reese is messing with the hologram via the computer and they go to capture her and the hologram of Dora goes to type up but cant so she tells Tia to do so but she cant and its revealed Reese is using her mind to block her. Sadiq carries Reese out and Doomsday Dora explains that though there are billions of dimensions, two are unique, their dimension and the adults dimension. Tia types up the stuff to start reuniting the dimensions but Liam is destroys the keyboard to stop Fizzys team messing with the machine and Sadiq comes back in and admits Reese escaped and everyone goes off to the room with Quantum Nexus. Ernesto realizes that Holly got teleported to the security room as even though she had the card, the system realized Holly wasnt the cards owner. Ernesto carries Fizzy on piggy back into the Quantum Nexus to show the card and trick the system which is successful.
The Quantum Nexus is revealed to be a ball of light surrounded by metal but Reese has already gotten there. The Sparticles and Holly and Serena get in but Tia, Jeffrey and Liam get left behind outside when the door closes. She starts attmepting to destroy it with her mind but she doesnt succeed even though she throws Sadiq to the floor with her mind. Reese is revealed to have reset the system that Tia used to start reuniting the dimensions earlier by mistake. She shows Fizzy and Holly their parents and even though Holly still doesnt want the adults back she goes off to stop the cooling system which is the only thing that can stop liquidating it and Serena and Callum come with her. Callum searches for the right cable to cut but cant find it.
Outside, the screen shows the computer system starts locking onto a dimension full of volcanoes and theres minutes until it happens, Liam tells everyones whats going to happen and they and everyone in the Quantum Nexus room realize that the liquidation system cant be destroyed but Callum finds the right cable and Holly and Serena smash it. Fizzy exclaims the volcano dimension is coming with Reese retorting with told you so, but Sadiq tells her it was her fault. Jeffrey and Tia discuss their favourite memories of the past year before they die while lying on the floor, agreeing they've had the time of their lives with forty seconds to go. Back in the Quantum Nexus room everyone gets Reese to focus on her mother using her mind to try and bring the two dimensions together. She does this but the Quantum Nexus overheats and Doomsday Dora to help but she disappears. The countdown ends and Tia and Jeffrey cling onto each other however nothing happens and then a girl asks about Reese and introduces herself as Muna. No one has died and they realize the machine had broken just before it overheated and reunited the wrong dimensions.
Then, other kids walk in and a girl introduces herself as Cara, which is the name of Reeses mother and they realize Reese managed to bring her parents and the adults back as teenagers including Dora and Hollys parents. Tia, Jeffrey and Muna then walk in and Muna embraces Reese while Tia asks who'll be in charge.
- Final appearances of Tia, Jeffrey, Liam, Callum and Muna.
- First appearances of Brian (Fizzy's dad) and Kim (Holly's mum).