The war between Ishgar and the Alvarez Empire rages on as the forces of the empire occupy the guild building of Fairy Tail. With Makarov sacrificing himself in order to take out the majority of their enemies, Larcade Dragneel enters the battlefield with the intent to seek revenge: with his aptly-named Pleasure, Larcade overwhelms friend and foe alike who have experienced the "forbidden" pleasure with that "pleasure" itself. However, he is forced to change his plans because of Zeref, and Larcade instead focuses on the enemies in front of him; Yukino attempts to summon a Celestial Spirit in order to fight back, but is assaulted by tentacles of Pleasure (as are Frosch and Lector), which begin to overwhelm her.
In the nick of time, Kagura appears, saving Yukino and questioning how a wielder of light could be allied with Zeref; Larcade reveals to them that Zeref is his father, and that Natsu is his uncle. The battle between the two then begins, with Kagura finding a way to stop the Spriggan's Pleasure through pain. However, even that is insufficient as Kagura is unable to land a single attack, even with her unsheathed Archenemy, leading to her swift, bare-handed defeat. Turning his attention to Yukino once more, Larcade psychotically expresses his desire for her to die. Sting, meanwhile, thanks to Freed's help, has made it to the battlefield and is search of his friends; he picks up a familiar scent and heads towards it. Concurrently, Yukino is about to be killed as the Exceed and Kagura are forced to watch. Lector tearfully calls out for Sting to come and help them, citing him as their last hope, and by sheer coincidence, Sting jumps into the scene and delivers a swift, White Dragon Slayer Magic-empowered kick to Larcade, apologizing for his tardiness.
With Sting musing that Larcade did a number on his friends, the Spriggan 12 member, unfazed, dubs Sting as another fool that dares to stand against him. Sting's subsequent punch does little more than push Larcade back, with the latter responding by assaulting Sting with his Pleasure. Before Yukino can finish her warning about the nature of this attack, Sting devours it, noting that nothing "white" will work on him, citing it as the main advantage of a White Dragon Slayer. He then gives Larcade a dirty look, not pleased with the fact that the Spriggan's smell is identical to Natsu's.
Demanding an explanation, Yukino and Lector reveal what they've previously learnt about Natsu's relation to Zeref and Larcade; Sting brushes the complicated relationships aside, claiming that people can smell similar, but that Larcade and Natsu shouldn't smell exactly the same. As a response to this, the Spriggan cryptically dubs Natsu as, in a way, Zeref's child, and launches several blades of light towards Sting, all of which the Dragon Slayer devours, reminding him that light and white things have no effect. Sting then attacks with Holy Ray, and, while Larcade is distracted, appears right in front of him and delivers a point-blank Holy Nova, throwing him into a nearby hill. Even though Larcade acknowledges Sting's prowess, he quickly rejuvenates and reveals another Magic in his arsenal: Famished Soul, which afflicts people with insatiable hunger. Weakened by his affliction, Sting is unable to move, which Larcade uses to attack Sting with the cross on his back. Hearing the spectating Lector's voice, Sting turns around, but sees Lector as food, not as his friend.
Yukino, Kagura and Frosch are affected as well (though the latter to a much more limited degree); the former two attempt to eat other while Sting does the same to Lector, with Larcade commenting that it is fitting for them to die eating each other. Realizing what is happening, Sting knocks out his friends in order to stop them from eating each other, but he remains fatigued from hunger. Larcade easily dodges Sting's attempts to hit him and retaliates, batting him around and hitting him with the same move that defeated Kagura. Undeterred, Sting announces that he is the Master of Sabertooth, yet Larcade, not having heard of the guild, brushes Sting off and impales him with the cross he launched earlier.
The Spriggan proceeds to belittle his opponent for not being from Fairy Tail, advising him not to interfere. Sting exclaims that the very reason he is fighting is for Fairy Tail's sake, as well as for his friend Natsu. He pulls out the cross as Larcade reveals that his main goal is to take Natsu down. However, before Sting can do anything, Yukino's unconscious body is transported away and in her place, Rogue appears as a result of Minerva's Territory. Announcing that his Magic Power is critically low, Rogue offers what remains in the form of a torrent of shadows; Sting hesitates, knowing that it's a different element, but realizing his friend's strategy, devours Rogue's shadows. While Larcade preparing his finishing Magic, an angry Sting enters Dragon Force and, thanks to Rogue's help, actives White Shadow Dragon Mode in tandem with the Dragon Slayer's ultimate power. With Rogue cheering him on, the empowered Sting steals Natsu's catchphrase just as Larcade threatens to show Sting his final Magic: R.I.P.
Yet again, Larcade belittles Sting for his insignificance; the Dragon Slayer announces his goal, having idealized Natsu for as long as he can remember. He then offers Larcade a taste of Sabertooth's combined power and, charging at him with two elements in hand, successfully pushes the Spriggan back.
As the Larcade gets back on his feet, he tries to cast his Magic, but it is burned away due to its elemental affinity. A shocked Larcade then receives a strike to his chin, with Sting rushing at him with a shadowy strike, and then a combination of the two elements. In spite of this, Larcade remains arrogant, believing that no human can fight against the final desire in his arsenal. He then manages to cast R.I.P., causing Sting to immediately feel the need to sleep. Hearing Larcade describe his Magic as one that inflicts permanent sleep, Sting attempts to fight against this by striking his own injuries, hoping that pain can stop the effects of R.I.P. This is to no avail, however, as Larcade once more exclaims that no one can defy their desires, not even Acnologia, calling himself the ultimate Mage, and the only one that can best the Dragon King.
Sting turns his attention to Rogue, who, on the ground, is overcome by the same drowsiness. The Shadow Dragon Slayer gives him advice: to his shadow, as merging with them allows the user to strengthen their senses and thus escape the drowsiness for a moment. Unsure of how to make use of his new power, Sting questions how he should do this; Rogue tells him to "feel" gravity so that he will start to sink. Despite this advice, Sting is unable to perform the feat, but Kagura offers him help in the form of Gravity Change, which forces Sting to sink into his shadow. Finally, Sting finds himself within the world of shadows, confirming the truth in Rogue's words, as his senses become ever sharper. In shadow form, Sting fires himself towards Larcade. Though the latter states that he can see him coming and prepares to strike back, Sting appears from within the shadows and pierces his target with his and Rogue's combination spell; White Shadow Dragon's Rough Silk fatally strikes Larcade, who falls to the ground. As his friends smile upon seeing his victory, Sting states that the only one to sleep will be Larcade himself. Larcade, meanwhile, calls out for his father in abject disbelief.
Some time later, Minerva and Yukino make their way to Sting and Rogue's location. As they question the Twins' injuries, Sting notices their presence, while Rogue apologizes for being unable to stand up. With Larcade lying nearby, unconscious, Lector and Frosch run towards their partners; Sting embraces the former, praising both Exceed for getting through the battle. Much to Rogue's confusion, Frosch proposes eating together, a leftover effect of Larcade's Magic. Upon seeing this, Yukino laughs, but Minerva notices that one more person is present; she walks to Kagura, asking if the Mermaid Heel Mage had fought together with Sabertooth. Recalling the events of the Grand Magic Games, Minerva apologizes to Kagura for what she has done to her, but Kagura brushes it aside, claiming that she does not intend to let grudges get in the way of her life anymore. With the whole group completely exhausted, they decide to let Fairy Tail handle the rest, though Kagura in particular wishes for Erza's survival.