Submitted by Tornado Dragon
It is revealed that Valentine has reconstructed the MEDUSA (a quantum energy weapon used during the Sixty Minute War) inside St. Paul’s Cathedral in London, and the Old Tech he stole from Hester’s mother Pandora after he killed her was the weapon’s computer core. He intends to use the MEDUSA to bring down the Shield Wall that protects the non-mobile city of Shan Guo from the traction cities, which will enable London to access it, claim its resources, and use the lands beyond as a whole new Hunting Ground.
As London is approaching the Shield Wall, Hester discovers that Pandora hid the MEDUSA’s crash drive in the eye pendant she gave her before her demise, so with help from Tom, Anna Fang, Anna’s Jenny Haniver airship, and the Anti-Traction League of Shan Guo, Hester gets onto London and plugs the crash drive into the MEDUSA, deactivating and destroying it before it has completely breached the Shield Wall (though Anna and most of the League die in the midst of this). However, Valentine refuses to give up, and sends men into the Wheelhouse to kill the Navigators and wreck the brakes so London will ram itself through the remainder of the wall.
When Valentine tries to flee aboard a flying vessel, Hester confronts him, and he soon reveals that he is actually her father before they engage in a fierce fight. Meanwhile, with help from Valentine’s disillusioned daughter Katherine, Tom flies the Jenny Haniver into London’s “gut” and destroys the engines with a single missile shot, then flies out and collects Hester before shooting down Valentine’s ship. Though Valentine survives the crash, he is crushed to death moments later under one of London’s tracks just as it comes to a stop outside the Shield Wall.
Katherine and the surviving Londoners are allowed into Shan Guo to live in peace, and Hester and Tom take off in the Jenny Haniver to see the world.
After the Anti-Tractionist Anna Fang (Jihae) rescues Hester (Hera Hilmar) and Tom (Robert Sheehan) in Rustwater from both being sold into slavery and from Shrike (Stephen Lang) (who is after Hester because she broke her promise to become a cyborg Stalker like him), she takes them in her Jenny Haniver airship to the airborne city of Airhaven. There, they have a meeting with her and the Ruh-shan, the Anti-Traction League of the non-mobile city of Shan Guo, led by Captain Khora (Regé-Jean Page), and Hester deduces that this meeting is about her late mother Pandora (Caren Pistorius). Anna explains that Pandora found something dangerous before she was killed by Valentine (Hugo Weaving), and she was afraid of him and what he might do, so she told Anna to find Hester if anything happened to her because Hester would be able to stop him. After Anna implores her to try to remember the time when Pandora was murdered, Hester remembers that Valentine made off with a piece of Old Tech, but when Khora asks what kind of Old Tech, she says she doesn’t know. When Tom defends Hester by telling everyone that she was eight years old when this took place and thus can’t be expected to remember it all clearly, the Ruh-shan grab Tom and Anna demands to know what is being built in St. Paul’s Cathedral in London, but he has no idea.
Khora soon informs Tom that Valentine has been purchasing fusion inverter cells from Scavenger traders for the last six months, which grabs his attention because he earlier noticed Valentine taking an interest in such an item after London had consumed a smaller traction city. He draws a symbol on a piece of paper and asks Hester if that piece of Old Tech bore this symbol, and after she confirms it, Tom explains to all that what Pandora found was a computer core, which acts as a control system for a quantum energy weapon (a weapon used during the Sixty Minute War that was capable of annihilating whole cities). Accepting that Valentine has reconstructed this weapon – known as the MEDUSA – in the cathedral, Anna asks Tom how it can be shut down, and he replies that the only thing that can do that is a crash drive, which overrides the firing sequence and causes the weapon to self-destruct, but he believes that the crash drive is long gone. After Anna draws the conclusion that Valentine has a target in mind more important than any of the other traction cities, another member of the Ruh-shan enters and warns the others that London is speedily heading east towards Shan Guo.
As this meeting transpires, Valentine’s daughter Katherine (Leila George) and Apprentice Engineer Bevis (Ronan Raftery) (who told her that Valentine was responsible for pushing Hester and Tom off of London earlier on and is masterminding the building of something very secret and sinister in St. Paul’s) sneak into the cathedral via a hidden passage and discover Valentine finishing the reconstruction of the MEDUSA with the aid of Dr. Twix (Sarah Peirse) and her team, which he intends to use to destroy the Shield Wall that protects Shan Guo from the traction cities so London can access it, claim its resources, and use the lands beyond as a whole new Hunting Ground. Lord Mayor Crome (Patrick Malahide) finds out about Valentine altering London’s course and confronts him in the cathedral, upon which he sees the MEDUSA. Valentine tells him that this weapon is the future and whoever controls it controls the world, but when Crome completely disapproves of both the weapon and Valentine’s intentions, Valentine responds by shooting and killing him. After hearing the gunshots while sneaking back out with Bevis, Katherine tells Bevis that she is disowning her father as of now. Valentine soon gets on London’s video screens and informs everyone of his decision to direct London towards Shan Guo and his reasons for doing so.
Back at Airhaven, Anna tells the Ruh-shan that Valentine is going to attack the Shield Wall, so they must inform Shan Guo’s leader, Governor Kwan (Kee Chan). Suddenly, the city experiences a complete power outage, and Hester realizes that this is just a diversion to create chaos because Shrike is now here. Indeed, having followed Hester to Airhaven, Shrike breaks into the meeting room, and Anna and the Ruh-shan battle him while Tom protects Hester. Shrike soon starts a huge fire that quickly begins to destroy Airhaven, and Anna tells Hester and Tom to make a break for the Jenny Haniver. Soon after, Anna and the others inflict critical damage on Shrike before fleeing for their ships, but Shrike resumes his pursuit of Hester and stops her and Tom just as they reach the Jenny Haniver’s dock. When Tom tries to attack Shrike, Shrike dazes him and then prepares to kill him. Hester tearfully begs Shrike to let him live, and Shrike soon understands that Hester is in love with Tom. He then permanently shuts down due to the damage he sustained, but not before returning to Hester the eye pendant that she got from Pandora before Valentine killed her and then telling her that he is releasing her from her promise. Anna then appears with Ruh-shan member Sathya (Menik Gooneratne), and Hester and Sathya pick up Tom and they all board the Jenny Haniver just before Airhaven strikes the ground and explodes.
Hester and company arrive in Shan Guo ahead of London and meet with Governor Kwan, and Anna warns him of the impending danger and that they must launch the Allied Fleet in a pre-emptive strike. Tom protests this because he doesn’t want to see innocent Londoners perish, but Kwan tells him that there is no other way and gives the order for the first strike to commence, and Tom walks off in disgust. Just then, London is seen in the distance, so the Allied Fleet and anti-traction guns are made ready while Valentine prepares the MEDUSA. Hester chases after Tom to try to talk to him, but she gives up when he won’t answer her, after which she notices a strange carving of a head on a wall in a place of prayer. Upon examining it, she notices that it’s the head of the mythical Medusa and it has an eye identical to her pendant in the center of its forehead. She opens the pendant up and finds that the crash drive is contained within, and she runs and finds Tom and shows it to him, after which he says that they need to find Anna.
Dr. Twix activates the MEDUSA, and the blast wipes out the entire Allied Fleet, smashes the anti-traction guns into scrap metal, and blows a big chunk out of the wall, but not enough for London to pass through. As the weapon is readied for a second shot, Hester shows Anna and the Ruh-shan the crash drive and says that they need to get on London. She, Anna, and Tom get back aboard the Jenny Haniver and fly straight there with the Ruh-shan, and along the way, the MEDUSA fires again and increases the gap in the wall, and Valentine orders Twix to prepare the weapon for the decisive blast. The Ruh-shan ships go on ahead of the Jenny Haniver to draw the fire of London’s anti-aircraft guns away from it, and they succeed in taking out every gun and searchlight on the city at the cost of most of their lives. The Jenny Haniver reaches the cathedral, and before Hester jumps out, Anna gives her a gun and tells her to stay out of sight outside until she gives a signal for her to act. After Anna kills the guards outside the main entrance, she jumps out and goes right on in, leaving Tom to fly the airship.
Just as the MEDUSA is about to be fired, Anna appears on a balcony and shoots at Valentine. Vambrace (Mark Mitchinson) steps in front of Valentine to shield him and dies instead, and Valentine soon returns fire and wounds Anna. Valentine then takes Vambrace’s sword and goes up to Anna and has a swordfight with her, and while he is distracted with this, Hester sneaks in (having interpreted Anna’s gunshots to be her cue) as Dr. Twix and the other scientists are running away and plugs the crash drive into the MEDUSA. Just as Valentine fatally stabs Anna in her abdomen with a hidden knife, the upload of the crash drive completes just a split-second before the MEDUSA can fire, terminating the sequence and making the weapon destroy itself. Anna orders Hester to flee, then tells Valentine that it is all over before she falls to her death.
Valentine goes outside and meets up with an arriving Katherine, who lambastes him for his heinous actions. She tells him that he has failed since the wall is still standing, but he replies that that wall WILL be coming down, after which she hears gunfire up in the Wheelhouse. She hurries up there to find that her father had a couple of his henchmen murder all of the Navigators and take out the brakes so London will ram through the Shield Wall, which is drawing ever closer. Valentine tries to flee on one of the flying vessels, but the vessel is tethered to its dock, and when he goes up to the roof to disconnect the cable, he finds Hester waiting for him with gun drawn. After he soon reveals to her that he is actually her father, they engage in a fierce fight. Meanwhile, Tom contacts the Wheelhouse and gets Katherine, and after learning of London’s situation, he tells her that she will need to cut the city’s engines. When she replies that that is impossible because the controls are shot, Tom tells her to open London’s doors for digesting traction cities so he can fly in and destroy the engines with a well-placed missile shot. Tom accomplishes that very objective and flies out safely, then goes up to Hester and collects her just as she gets some distance between herself and Valentine before firing another missile at Valentine’s vessel and making it crash. Though Valentine survives this, he is trapped in the wreckage, and he is crushed to death moments later under one of London’s tracks just as the city comes to a halt right outside the Shield Wall.
When morning comes, Katherine leads the surviving Londoners up to the wall, where they are met by Kwan and his soldiers. Kwan soon orders the soldiers to lower their weapons and decides to welcome the Londoners into Shan Guo so they can all live in peace. Hester and Tom then depart in the Jenny Haniver to see the world.