Princess Fader takes a train to meet Isaac Nasser (aka The Dragon Lord) in a restaurant for a peaceful confrontation. The Lord of the Dragon's arrives several minutes after Fader and the maternal cousins greet each other cordially but frostily and, over tea, they argue about their past as close friends (Fader admitting then, as they dreamed of leading the world into a new era that she had known her younger sister Darkness was in love with Isaac and she herself had once shared his ideology), how their goals used to be aligned, and the blood troth between them, ending with Nasser telling his cousin to stay out of his way and making it clear he intends to burn down his enemy’s world, with or without Fader's help, and departing, leaving Fader sitting before a cooling cup of tea.
Meanwhile in the jungles of Kweilin, at night time, Iiron Scamander helps a Qilin, a magical creature that can see into one's soul as well as the future, give birth, but some of The Dragon Lord’s disciples, led by Luz Noceda, attack and overpower Iiron, Darkness swiftly delivering a fatal curse to the mother, and, after a short skirmish, the acolytes, knocking out Iiron, kidnap the newborn. Unbeknownst to them, the Qilin has birthed twins, the younger of which Iiron is able to save after he wakes up by the dying adult Qilin moments before the mother succumbs to her injuries and passes on, then leaving himself.
In his fortress headquarter of Nurmengard, high up in the Austrian mountains, The Dragon Lord greets his Dark Ones and after a short conversation with Luz, who he sends inside to rest, uses dark magic the Qilin to harness its ability of precognition after it doesn't bow to him, watched by a concealed Freddy Lupin (who had joined the Dark Ones in the last episode). In the Qilin's reflection, he sees Fader showing the blood pact to Perseus and Iiron in the Hog's Head Inn. Shortly afterwards, Freddy speaks to Luz. He tells her that The Dragon Lord regularly asked him to spy on the young woman and tell him her thoughts, but he revealed to Luz that he did not tell their leader everything. After that, Luz looked in a mirror and saw an inscription: "Forgive me", which she erased immediately.
Iiron and his brother Perseus head to Hog's Head Inn in order to question Fader for the best course of action against The Dragon Lord. With Fader still powerless to break the Blood Troth she had made with the Dragon Lord when they were young and desired to change the world, but that now prevents her from fighting her cousin, she reveals that she has plans to defeat The Lord of Dragons and stop him from tearing the world apart with hatred and suspicion, but they have to trust her and the three plan to gather a group of individuals to fight the Enemy. Kuvira (who has also been enlisted into the group Fader is gathering) recruits Batty, who is depressed with Freddy having left her and initially wants nothing more to do with the magic world but eventually decides to help out after Kuvira convinces her she is still needed. In the Great Wizarding Express heading for Berlin, Iiron, Perseus, Iiron’s assistant, Bunty Broadacre, Amity Blight, Nagini, Gus Porter, Willow Park and Yusuf Kama greet the two, who arrive via the Floo network, and Iiron, after giving Kuvira an introduction, then reveals that in order to thwart The Dragon Lord's future-seeing abilities, they will split up and perform different roles. He gives Perseus a tie with a large golden pin, Batty a coreless snakewood wand from Fader, and Bunty a letter holding within it Fader's instructions that will burn when she reads it. Kuvira meanwhile has been gifted beforehand with a Portkey book while Yusaf has his own instructions and as they pull into a station, Bunty and Yusaf set out to fulfil their roles.
Bunty has Iiron’s suitcase duplicated into half a dozen copies and Yusaf departs for his mission with the companions best wishes, while the rest go to Berlin in order to visit the German Ministry of Magic, where a gathering for the election of Supreme Mugwump is taking place. Passing the gathering of supporters for the two candidates, Lui Tao and Vicência Santos, Perseus uses his authority to gain access to the gathering of the International Confederation of Magic. Meanwhile, however, Dark Ones and members of the 13 Forsworn, including Fader's younger sister, Princess Darkness, the Dragon Lord’s wife and deputy, as well as Ex-Queen Wasp and Farland Kingsbrood/Chompy Mage, infiltrate the supporters and Wasp sets a Santos campaign poster alight, while Darkness watches on smiling.
Meanwhile, Fader’s army make contact with Anton Vogel, the Supreme Mugwump and the Minister, Iiron delivering a message to Vogel from Fader encouraging him to do what is right, rather than what is easy. Though Anton initially seems to take Fader’s words into consideration, thanking Iiron, despite referring to the Magicar Princess as one who would not leave her school when the world outside was burning, he subsequently gives a refusal to help Iiron and the others to stop The Dragon Lord for political reasons and they can only watch as The Dragon Lord is acquitted of all charges by the International Confederation of Nations, to the shock and horror of many present. The band subsequently notices Darkness, Wasp and several acolytes they remember from the rally in Milford present and Perseus attempts to take them into custody, only to be incapacitated by Helmut and kidnapped by the acolytes. Though Iiron attempts to go to his sibling’s aid, Kuvira stops him and convinces him not to act, realising that the Dragon Lord’s people have already undermined and taken control of the German Ministry. Outside, Farland has conjured into the air a massive campaign banner of the Dragon Lord’s cause while dozens more of the acolytes fire their master’s symbol into the sky around the ministry headquarters.
That same night, Fader dines with her brother Spirit in his inn, recounting their past, only for Spirit to cut her off with the reminder that he needed no reminder, as he had been there. A knock on the door which Fader answers interrupts them and the visitor is revealed to be none other than Principal Pincus. Pincus reveals the new position the pardoned Dragon Lord has achieved to Fader, to her disappointment, and is asked to take over Fader's morning classes, which she agrees to immediately, with the aided plead for Fader to be careful. Fader thus prepares to depart and, when Spirit asks if she's "off to save the world", Fader cryptically responds that such an action "would take a better woman" than her. Iiron, Batty, Amity, Gus, Willow, Nagini and Kuvira went to the German Ministry of Magic to look for information about Perseus, but receive none, the official they speak to simply answering that their Ministry had no records of Perseus' apprehension. Barry spotted Helmut and another and the group attempt to pursue them, Batty demanding at a shout to know where Perseus was. The man disappeared when a wall appeared out of nowhere in front of them, with Helmut on the other side - it turned out he was one of the local Aurors.
Reuniting with Fader the next day, she tells Iiron where Perseus is imprisoned and assigns Kuvira, Batty and the others of the Howlington Pack, who she had contacted, with the task of preventing assassination attempts on one of The Dragon Lord's competitors: Brazil Supreme Mugwump candidate, Vicência Santos. The Dragon Lord, at Nurmengard, then has a vision Yusuf Kama going to Nurmengard, and Fader going to Bhutan to confront him, with Darkness entering just as the vision fades. Ordering his wife to have his inner-circle acolytes prepare to depart on the morrow, the two watch as the dragon that guards Luz since her magic was revealed swoops over its owner, Darkness asking why it stayed with the young girl. As the dragon flew over Luz, The Dragon Lord concluded by saying that the phoenix was probably supposed to protect Luz in connection with his assigned task and assures Darkness that Luz’s pain made her more powerful than Fader. Next morning, Yusuf enters Nurmengard Castle and is promptly installed as a spy in The Lord of Dragons's inner-circle, after the Enemy seemingly removes Yusuf's memory of Ophelia's death.
Fader walks across Berlin with Luz following her as The Dragon Lord has ordered her to kill his cousin. Aware of Luz's spying, Fader quickly faces her, and they fight due to Luz's anger about her family supposedly being abandoned. Fader defeats Luz after a fierce fight, and it's revealed that she is not a pure human but rather Fader’s great-niece as the daughter of her nephew Thuviel. Meanwhile, in Berlin, the Dragon Lord has been allowed to run in the election. Anton Vogel defends his stance on The Dragon Lord running as a candidate for the next Supreme Mugwump to other high-profile ICW members, who are appalled. Isaac is on the same street, driven in a car with Darkness. He sees a vision of Batty pulling out her coreless wand to threaten him, then is pulled out of the car by his thousands of cheering supporters, who crowd the street.
Batty, Kuvira and the other four attend the dinner as instructed while Amity, Nagini, Willow and Gus patrol . The Dragon Lord soon arrived with his entourage, including Yusuf and Freddy. Batty attempts to speak to Freddy as he passes her, but he didn't even look at her, while Amity searches without success for Luz. Kuvira is able to prevent the assassination of Vicência Santos but Batty's reckless face-off with The Dragon Lord, who secretly manipulates her threatening movements via magic, allows The Wolf to frame her for attempting to kill him. Another wizard saw the altercation between the two with Batty holding Nasser at wand-point and yelled "assassin!", the dinner breaking into a frenzy. Kuvira casts a spell with her wand, making it appear as Batty's wand was actually magical, creating a weather storm within the hall, making all the wizards present, including the enemy, exit in the chaos.
The six army members barely escape, giving Isaac Nasser an incentive to turn the wizarding world against the allies. Freddy secretly aids in their escape by launching a chair at Helmut and his henchmen to distract them as Yusaf gently leads him away and buy Batty and the others more time to escape, the twelve escaping via Kuvira’s Portkey book. Meanwhile Iiron enters the Erkstag prison and successfully rescues his brother despite the guarding Manticore and the warden attempting to stop them.
The group reunite at Howlington Academy's Great Hall, where Iiron and Perseus find Kuvira giving several students career advice while Batty ate and spoke with some others. After all the students leave for their lessons, the brothers learn of their foe’s new position and go to the Hog's Head for dinner. Before leaving for dinner, Batty quietly walks through her old school, contemplating despairingly of Freddy. Freddy, himself, meanwhile, walks similarly through the corridors of Nurmengard, looking back at his choices with regret, regarding the dark path he had gone done and wishing to return to his friends but concluding that it is far too late for him and that his mistakes have crushed his chances to redeem. The two weredogs share a duet (Someday), where they wonder if they can be together one day.
As the Dragon Lord uses Necromancy in order to zombify the Qilin he killed in front of Luz, King, Darkness and Anton Vogel (who is secretly one of his supporters), subsequently having a vision of another Qilin and getting furious at Luz and King, Fader confronts Luz’s mother, Camilia (who, following her husband’s death years ago, has grown deeply averse to magic) about her responsibilities to Luz, encouraging her to take up her wand again, and Iiron learns the truth about Fader's past as Luz, disillusioned with The Dragon Lord, secretly contacts them via a mirror asking to return home. Fader comes up with a plan to save everyone with Luz and King's help, and the next day, she tells the others that they must go to Bhutan to stop their enemy, as the election will be held there.
Travelling to Bhutan with a device provided by the Room of Requirement, each with a suitcase, one the true one, the other fakes. They split up and, after several battles, are able to defeat all of Isaac's disciples based in Eyrie to attempt to seize the Qilin assisted by the traps Fader had placed within the copied cases, with Yusuf revealing his true allegiance in process. Batty also met Freddy, who she wanted to persuade to return, but he insisted that it was too late for him, stating he had made far too many mistakes to return. Moments later, they were captured by Darkness and several acolytes, who have secretly pursued Freddy, and led to the ceremony. Iiron, meanwhile, nearly reaches the election stage, but bumps into Henrietta Fischer, secretary to Vogel, who claims that Fader had contacted her, a claim Iiron is uncertain whether to believe due to the presence of so many Dark Ones. Fischer takes the case from Iiron after several Dark Ones stunning him and proceed onwards, while Iiron awakens among the feet of the crowd. Pursuing Fischer, Iiron later discovers the case he has is a fake after it Fischer turns and makes as if to hands the case to the young wizard, only for it to disintegrate in Fischer’s hands.
The Dragon Lord uses the zombified Qilin to be announced as the Supreme Mugwump to the watching world (including Yellow, Flashhart, Pincus and the rest of the Howlington Park, standing among the crowds of werewolves and city citizens watching a magical vision of the scene from the city) and has his people bring Batty before him from where she and Freddy are being held among the small party of Dark Ones right before the candidate. After Darkness takes Batty's wand and strides forwards to pass it to her husband and master, the Dragon Lord makes a speech to the world at large, immediately declaring war on the Day Ones and oppressors, to his millions of gathered followers and supporters cheered delight, torturing Batty, for her attempts to assassinate him and to make an example of her. Santos, however, swiftly undo's the spell, leaving the young weredog comforted by Freddy, who had broken free of his overseers.
However, Luz, Freddy, and Iiron are able to expose The Dragon Lord, Luz denouncing the 'Qilin' to be dead, before Darkness cuts her off with secret dark magic, and Bunty reveals the true Qilin. It chooses Vicência after Fader refuses to be the next Supreme Mugwump. His plans having been foiled, The Dragon Lord angrily attempts to kill Luz, who Darkness has weakened, but Fader and Camilia save her. As she was protecting Luz rather than attacking her cousin in the clash, the blood pact finally breaks, and Fader immediately battles the Dragon Lord. The intense battle ends with their wands on each other's head and their hands on the other's heart, reaching a stalemate, and Fader moves herself away from the Dragon Lord, who sneeringly asked who will love her now. Most of the small crowd of officials, bar the Dragon Lord’s followers, attacked then, forcing the Dragon Lord before a ledge. Telling Fader and the crowd that he was never their enemy, not now or then, The Dragon Lord subsequently retreats.
The weakened Luz is reunited with her mother, girlfriend and best friends and is taken away for recovery by her mother at the healing centre of the First Nome as the Dragon guarding her follows them while the friends seat themselves on the empty steps, Freddy sitting slightly away from the rest until Batty seats herself next to him comfortingly. In the aftermath of the election, Howlington celebrates its birthday with most of the group, Freddy and Yellow attending, reuniting Iiron and Yellow. Fader watches from a distance as she thanks Iiron for all he's done before walking away alone.
Troubled times are still ahead for Iiron and his friends. Even with The Dragon Lord thwarted, he is still out there and he has began his plans to take victory, even if by force, and the Global Wizarding War will truly begin soon. While the heroes are given a brief respite and moment of happiness, it is clear the road ahead will be filled with many difficulties even after this victory …
- Eddie Redmayne voices Iiron Scamander — An aspiring and introverted Magizoologist (a wizard who studies magical creatures) and enemy of the Dragon Lord. He is a confident of Princess Fader, despite being an outcast from certain circles of Wizarding society due to his checkered past. He served as the co-leader of the band of individuals united to fight the Dragon Lord.
- Katherine Waterston voices Yellow Amarillo del Bosque Verde
- Callum Turner voices Perseus Scamander
- Elizabeth Nabben voices Batty -
- Jessica Williams voices Kuvira
- William Nadylam voices Yusuf Kama
- Victoria Yeates voices Bunty Broadacre
- Mae Whitman voices Amity Blight
- Issac Ryan Brown voices Gus Porter
- Tati Gabrielle voices Willow Park
- Claudia Kim voices Nagini
- Ilai Swindells voices Freddy Lupin - A young weredog, a member of one of the most ancient and powerful werewolf families and Batty's best friend and love interest. He is a powerful and natural-born Legilimens (a person who can read others minds like a book). This power, however, has given Freddy a heavily-ingrained hatred of seeing the suffering of others and a wish to bring equality between werewolves and dogs and led to him being convinced that The Dragon Lord will make his dream of of bringing equality to his birth people (wolves) and his fellows (dogs) come true, as well as answer his questions regarding why he possesses such different powers, he went rogue and joined his side, eventually abandoning his best friends and father and becoming a Dark One and one of the youngest members of his inner-circle, telling his new master how to approach Luz Noceda. He later grows disillusioned, however, and returns to the pack and the side of good.
- Sarah-Nicole Robles voices Luz Noceda
- Alex Hirsch voices King
- Aleksandr Kuznetsov voices Helmut
- Oliver Masucci voices Anton Vogel
- Valerie Pachner voices Henrietta Fischer
- Ramona Kunze-Libnow voices Edith
- Dave Wong voices Liu Tao
- Maria Fernanda Cândido voices Vicência Santos
- Victoria Zerbst voices Aggie Bean
- Lottie Guntank voices Kitty Nguyen
- William Cottle voices Ivan Bewulf
- Sam Alhaje voices Omar Omari
- Victoria Zerbst voices Wendy Smersh
- William Cottle voices Winslow Spectre
- Raechelle Banno voices Scarlet Jagger
- Mads Mikkelsen voices The Dragon Lord
- Poppy Corby-Tuech voices Princess Darkness - The Dragon Lord's right-hand woman, deputy and wife, Fader's disowned younger sister and an exceptionally powerful witch and traitorous Dragon Rider.
- Anne Heche voices Princess Fader
- Kelly Butler voices Principal Pincus
- Bart Soroczynski voices Prince Grimler
- Susan Sarandon voices Orazira D'Mer-Buckthorn