Toaru Majutsu no Index Light Novel Volume 18

Chapters

 * Chapter 5: The Mercenary and the Knight's Encounter and Clash — Another_Hero.
 * Chapter 6: The Destruction of the Knight and the Princess's Defenses — Safety_in_Subway.
 * Chapter 7: The Astounding Enemy of the Princess and the Queen — Curtana_Original.
 * Chapter 8: The Queen and the Country's General Elections — Union_Jack.
 * Epilogue: The State and the Black Curtain's Increasing Foes — Next_Step.

Summary
Starts out with Aqua fighting against the royal knights. He takes them down easily and manages to get Villian to safety using his magical horse. It seems Villian has a crush on Aqua, and cries as he sends her away with his horse. Aqua than fights against Knight Leader one on one. They seem evenly matched at first, but Aqua hasn't fully healed from the battle at Academy City while Knight Leader has Carissa's blessing. Knight Leader tries to convince Aqua to leave Britain, but Aqua's answer was "talk is cheap." They crash again and again. As Aqua starts to gains upper hand and is about to strike him down, Knight Leader uses his spell which can turn any damage from any kind of weapon in his sight to zero. Aqua uses last hidden blade hidden within Ascalon, which Knight Leader didn't recognize as a weapon, to take him down.

Touma manages to smuggle in train that's headed to Forkstone. There he meets Floris, Who is a member of the New Light. She was captured by Necessarius at first, but the knights took her back to silence her. Floris asks Touma to help her get out of here. She asks for a key to get her out of her restraints, but Touma uses his Imagine Breaker to break it instead, and alarm goes off. In state of panic, the two jumps off from the train.

Anieze, Lucia and Angeleen managed to escape from the knights, but not the rest of her team. They get on board of a train where they're holding nuns captive in order to rescue them.

Touma managed to get to Forkstone with help from Amakusas sent to search for him. Floris was handed to them (without the knowledge that she was one of the New Light) as well as Villian, whom he came across after jumping off the train. At Forkstone he encounters Acqua fighting against the knights as well as Index laying unconscious inside the carriage, and Carissa. Carissa uses Curtana's power to create huge shock wave and sends them flying before they get a chance to fight.

Aqua managed to save both Touma and Index. Aqua tells him that Fianmma is after Imagine breaker, and now he is going after Fianmma instead. They come to short truce. Aqua leaves to do his own thing, and Touma regroups with Kanzaki and Amakusas. They come up with a plan to attack Carissa, who is at Buckingham Palace right now. The Buckingham Palace works like a lightning rod. In case Curtana goes out of control she'll be able to let the power escape via royal subway. There's special Cart that works as hub for the system, and the plan is to use that to attack her instead. They'll feed energy from Caven Compass, a flying fortress Necessarius has.

Touma, Index and Villian are the only ones that can go in since they got heavy security against magic in London and only royalty can access royal subway. With Index's help they manage to sneak in underground which was closed off to the public. There the three takes down huge paper mache security guard and encounters servants and maids working at the palace. As soon as Villian opens up royal subway Itsuwa calls Touma, telling him that they managed to access the hub cart and to get out before they get caught in explosion.

The explosion was not enough to kill Carissa, but enough to put her to 50% output. After the explosion London was filled with magic flammable energy from Curtana, so Touma and co. have a feast while waiting for rest of the Necessarius to gather and the gas to die down.

Anieze is also a big eater like Index, then she and Index starts to steal food off each other during a really messy dinner before the final battle (Index completely overwhelmed her). During the whole mess Touma is shown unable to get his hands on some food seeing as how rough the nuns were in their fight for food. After that Index meets up with other nuns that used to take care of her when she was still in England (though Index don't remember any of them), and got fed enough by them that she's asking them to stop.

Tatemiya and the other male members of Amakusa pushes the fairy-cosplay onto Itsuwa and tries to persuade her to use it on Touma. Itsuwa is a bit disturbed that the three sizes of the clothes fits her perfectly. Kaori comments aside that she's glad the Amakusa isn't directing this at her, Tatemiya then asks Kaori whether she'd like to counter Itsuwa using the fallen-angel outfit or the Ero-fallen-angel-maid outfit (Apparently he snuck into the Necessarius girl's dorm and stole those outfits). Kaori is starting to consider maybe it was a mistake to put her life on the line to save the Amakusa from the Knights. Other male members comment even though they'd be killed for sure if they tried to see the duel between Itsuwa and Kaori's using fairy and fallen angel cosplay, they're almost willing to risk their life to see it regardless.

Anieze's group overhears the Amakusa's furore and starts to discuss among themselves out of their 250 nuns who would be the best representative to take on Itsuwa and Kaori in this battle, and the tall one of the two nuns is being persuaded by the short one and Anieze to dress up in a imp-cosplay.

Orsola and Sherry was discussing something else, but moved onto saying Sherry needs to replace her worn out gothic clothes, and Orsola pulled out a goddess goth-maid costume for her. When Sherry denied and says Orsola has no understanding of gothic fashion, Orsola said it's a waste to throw that away and decides to put it on herself. Sherry panicked and stopped Orsola saying it's a bad idea for someone as well endowed as her to wearing something as revealing as that.

Acqua is trying to escape from the 3rd princess, who's trying to thank him for all his troubles. He's starting to regret saying some of things to her to calm her down, thinking it might have been a bit over the top. Oriana Thompson is helping her tracking him down (just to put it into context, Oriana's specialty is losing people that's following her, so she's very capable of tracking other people down).

The political situation in England is still ruled by the Royal family and the Queen rather than other politicians is because ten years ago a faction of politicians tried to sacrifice the 3rd princess in the process of eliminating all of France's military force, both magical and otherwise. If it weren't due to Acqua ignoring the political constraints and helped the 3rd princess she would've died. After that the Queen basically gave them a good thrashing using the artifact Curtana the 2nd.

Witches, who Necessarius has hunted since its founding, has finally shown up in the novels. They are in a alliance with Necessarius against the Knights for some reason. The witches are in control of a flying fortress that has a wave-motion gun.

Last battle against Carissa. They enter London with air support from flying fortresses. Curtana can slice dimension and create aftermass as a result. Carissa uses that to attack Touma and rest of Necessarius and Villian). Touma and Villian gets to Carissa first, and start fighting. After Touma gets good beating from Carissa and Griffin Sky (80 meters wide hang glider that can turn its own shadow into huge stake to attack), Kanzaki shows up to save him and others start to show soon after. They start taking down Griffin Sky, but Carissa orders the military ship by the coast to fire bunker cluster missile at the palace.

The first princess Rimea finds out Carissa's other reason for the coup. She wanted to do away with Curtana as well as protect England, so she decided to kill rest of royalty and destroy everything that's related to Curtana. By leaving her name and Curtana in history as a symbol of tyrant, the people won't allow the royalty to create another sword like it and do away with the royalty for good, or so that was her reasoning. Rimea asks the knights to help her if they feel slightest amount of pity towards her.

Touma manage to stand up and tries to fight Carissa. Carissa orders second bunker cluster to finish them off, but before it could strike Knight Leader shows and stops the missile. Aqua shows as well after destroying radio towers around the area. Kanzaki joins after patching herself up. All four of them team up for while but eventually Carissa gains upper hand by attacking regular mages and knights around to stall saints and Knight Leader.

Queen finally shows up. She says that what Carissa came up with is pathetic, arrogant and nothing more than a show of cowardice. Carissa was ready for show down between two Curtana, but the queen throws her's away and tells her that "if you want a change, you have to do something original as this." She takes out English flag as well as welsh flag and calls out the entire country to join the party. She spread Catena's power to entire population of England. "This country isn't as cheap as you think it is", she said.

Everyone around London starts to show around the palace and starts fighting against Carissa. If Carissa loses her focus, original Curtana's power will be sucked dry by the people, so she has to take on flying bartenders and fireball throwing maids while trying to keep it under control. During the confusion, Acqua throws Touma to Carissa via Ascalon and he destroys Catena as well as Carissa's face. Carissa is shot across the palace.

Just as everything was about to end well, Fianmma shows up. Carissa is laying on a road all by herself and Fianmma starts talking to her if he should kill her or not. Touma comes in before Fianmma could strike and saves her. Fianmma shows the remote he got and despite Carissa's warning he activates the remote, summoning Index's John's Pen Mode right in front of Touma, and uses her to attack him. After seeing how remote works, Fianmma leaves.

Sasha in Russia is on the run with her boss, and Vent helps her escape.

Archbishop and the queen claims that having a remote control was only natural. They wouldn't have left Index in Academy City without some sort of safety device. There's only two remotes, one with Archbishop and other with queen. Fianmma took queen's remote. Stiyl is outraged by this. Index will be put under their care for now. Touma asks Stiyl to take care of Index and decides to head to Russia to give Fiamma a good one. Touma hid two things from everyone: one is the fact that Fiamma has a ‘3rd arm', and it appears to be very similar to his own Imagine Breaker, except that Fiamma's power can manifest outside his right arm. The second is the fact his own memory's lost. He plans to find Fiamma in Russia, and after hearing the full details on their connection he plans to beat the pulp out of him. End of volume.

credit: The observer, from OM, Bob4000, and Lummie from AS