The sun has begun to set at Anistar City. On its northwestern border, Prof. Sycamore and his Squirtle sit atop the Sundial, which is a giant pink crystalline structure towering over a dish of golden rings. Sycamore muses to himself that the Sundial tells the time by casting shadows, which is in turn determined by the position of the sun. However, due to the advance in digital technology in modern times, people no longer depend on the Sundial to keep track of time, not even those who live in Anistar. According to his knowledge, the Sundial's shadow position at the Anistar Gym means it is 6pm in this season, and he checks against his watch to see that it is indeed accurate.

However, the truth is, the Sundial doesn't simply tell the time but constantly gives off a certain pulse wave as well, which his wave manometer has managed to pick up. Every day between 8pm and 9pm, this mysterious wave becomes particularly strong, although its significance is so far unknown. Yet, he believes that his investigations are on the right track, which is why he has come personally to Anistar. That said, sitting so high up on the Sundial, he actually feels a chill down his spine, not because of the cold twilight air but because of the sense that something or someone is right beside him. He hopes that it is just his imagination, but he could almost feel its breath and hear its heart beat. Suddenly, something fast moving swoops past him, and the young professor lets out a yelp. He soon realizes that it was just a flock of wild Spritzees, and sighs in relief. Staring at the Sundial's shadow, he wishes that the next two hours would go by quickly, but remains completely oblivious to the giant green serpentine creature that is lurking behind the crystalline structure.

At the Lost Hotel, Ramos throws a fit, and couldn't believe that Green allowed the young trainers to head to Anistar on their own. He demands to know if Green is aware of their situation, and Green states that Diantha has explained to him. However, according to what he heard, someone in Team Flare possesses the ability to shape-shift, which means the enemy could also be among them. Ramos doesn't like what Green is implying, and barks that they have no association with Team Flare. Diantha quickly tries to pacify the old man, and Green remarks that he is simply raising a possibility to illustrate the point that every place is equally dangerous for the kids, which is why he deemed it a good idea for them to meet up with Prof. Sycamore who appears to have crucial information to share. For safety measures, he has lent them his Charizard and Rhyperior, and in fact, the girl named Y who acted as the group's leader wanted him to pass on an apology to Ramos for going off on their own.

Gurkinn laughs that Green's way of delivering the apology is amusing as usual, and Ramos is shocked when Green greets Gurkinn as Master. It turns out that Green is one of the 17 disciples of Gurkinn, and has succeeded the skills of Mega Evolution from him. Gurkinn giggles that although the virtues he teaches also involves character building, he sometimes chooses to keep one eye shut towards certain personalities, which causes Ramos to become speechless.

Meanwhile, the Vaniville kids are making their way through Dendemille Town where snow is heavily falling. Trevor shivers from the cold, and Shauna feels lucky to have Green's Charizard keep them warm with the fire on its tail. Y believes that Charizard is the evolved form of Salame, and X acknowledges the fact with a grin. He states that Green's other Pokemon, Rhyperior, is also the final evolution of Rhyhorn, and everyone could see that Salame and Rhyrhy are both looking up to their seniors, clearly aware of their association. Trevor recalls how menacing Green appeared when they first met, but now realizes that it is just the utter strength that he emanates, which is also reflected in his Pokemon. He steals a glance at his Flabebe, Tierno's Corphish and Shauna's Skitty, and from their determined looks sees that the three have apparently been inspired as well, and are aspiring to attain such level of strength some day.

Exiting the eastern gates of Dendemille, the group makes it across the snow-laden Route 17 with the help of a herd of Mamoswines, and finally arrives at Anistar City. Having escorted the kids to their destination, Charizard and Mamoswine bid them goodbye and start to make their way back to Green.

Y wants to know where they are meeting the professor, and Trevor points towards the giant crystalline structure just north of where they are. He explains that Prof. Sycamore will meet them at 7:50pm, but before he could finish his line, the kids suddenly notice that something is going on atop the crystalline structure. The group hurries over, and are horrified to see a group of humanoid birds attacking Sycamore, who is left suspended in midair by his safety belt. Y quickly reaches for her Pokeballs to attempt a rescue, and wonders what Pokemon they are. X discovers them to be Hawluchas with the Pokedex, and tells Y to focus on helping the professor while he deals with the creatures.

Sending out her newly caught Absol, which she nicknamed Solsol, Y orders a Psycho Cut, and the attack swiftly severs the rope tied to Sycamore's safety belt. As the man begins to fall, Y gets Croaky to create a safety cushion with its frubbles, but Sycamore loses grip of his wave manometer during his plummet. Fortunately, Veevee catches it with its ribbon-like feelers and is assisted by Fletchy to land safely back onto ground. The four Hawluchas start to swoop down as soon as Sycamore tumbles into the frubbles, and X sends out his newly captured Pinsir, which he nicknamed Rute. The Pinsir keeps a calm composure and even closes its eyes as it evades the four Hawluchas' attacks, and both Tierno and Shauna are amazed by its senses. The four Hawluchas then decide to pull off a simultaneous Brave Bird, and begin skydiving towards Rute. However, before they make contact, Kanga, Garma, Elec and Marisso each targets one with their attacks and floors them all.

While X's Pokemon keep the Hawluchas busy, Trevor helps Sycamore to his feet, and the professor once again bows in apology to the kids for what he put them through. Trevor stammers uneasily that it is really alright, and wonders what it is that the professor wishes to tell them. Gesturing towards the crystalline structure, Sycamore says that it is something about the giant Sundial, and Y is astonished to hear that it isn't just a fancy decoration of the city. Sycamore explains that it is strongly associated with Mega Evolution, and reminds X of the battle they had at his Science Lab. Sure enough, X remembers how Marisso and Salame fought against each other, and the young professor reveals that his wave manometer has managed to record a certain wave at that time. From his conversation with Trevor afterwards, he eventually figured out that the wave originated from X's Mega Ring, and Shauna recalls that Team Flare also once mentioned about such a thing. Sycamore says if one is to be meticulous, the wave actually comes from not the Mega Ring but the Keystone it holds. The interesting thing is, the Sundial also gives off a similar wave, which means the two are of comparable composition.

The revelation causes the kids to gasp in bewilderment, but they are more shocked when Sycamore states that ever since the Ultimate Weapon has bloomed, the waves given off by the Keystone and the Sundial have become synchronized. The truth is, the young professor has been following these wave patterns ever since he discovered them. With the regular Holo Caster messages Trevor sent him, he has checked their whereabouts against the wave manometer's tracking of X's Keystone location, which have been consistent so far. Yet, after the Geosenge incident, he could no longer track them, and this is proof that the wave emanating from the Keystone has changed in wavelength. Trevor wonders why it is the case, and Sycamore believes that the beams given off by the Weapon must have caused a change chemical change in the minerals.

Sycamore informs the Vaniville kids that another characteristic of the wave is its drastic increase in amplitude between the hours of 8pm and 9pm, a quality which has remained unchanged even after the Ultimate Weapon's activation. The young professor believes that something will surely happen as soon as the clock strikes 8pm, which is 30 seconds later, and the group stares intently at the wave manometer as the signal detected starts to grow exponentially in intensity. Then, at 8pm sharp, both X and Y's Mega Rings suddenly give off a blinding flash. The light given off by the Keystones hits Kanga, Elec and Garma, and Trevor exclaims that the Mega Stones they carry are also beginning to glow, just like when Mega Evolution is being activated. Sycamore realizes that the heightened intensity of the Sundial's waves is resonating with the Keystones, causing them to shimmer, which in turn makes the Mega Stones glow.

The young professor's rationalization immediately sparks a thought in X's mind, and he reveals that they are currently searching for the Absolite and Pinsirite, Mega Stones that could Mega Evolve Absol and Pinsir. He wants to know if the Keystone's light can really seek out the Mega Stones, and Sycamore replies that although he cannot be completely certain of all the mandatory conditions, it would appear to be possible. However, since the period of heightened intensity only occurs between 8pm and 9pm, the method could only work during this hour.

X pauses to ponder on the matter, and states that although he would really have liked to swiftly take down their opponents and start hunting for the Mega Stones, the Hawluchas are proving to be much tougher to beat than he expected, which implies that they are not wild Pokemon but are under the command of someone. A frown appears on his face as he decides on what to do, and he eventually asks Y if it is alright that he breaks the fifth rule of their pact again. Slipping off his Mega Ring, he hands it to Y, and wants her go search for the Mega Stones while he stays behind to protect the professor. Y begins to protest, but X says they don't have much time to waste.

At that moment, Tierno offers to take up the task, and grins that although he is not a Successor of Mega Evolution, hunting after the Mega Stones is something that he can manage. Y thinks it would be too dangerous since Team Flare could ambush him, but Tierno thinks he should be fine and reminds her that the Keystone's wave could no longer be tracked ever since its wavelength changed. As X has said, they seem to be dealing with some tough opponent there, which is why he thinks it is best that Y stays behind to help and leave the task to him. However, Shauna still voices out her protest, and says it is not good to go off alone. That said, she has decided to go together with Tierno, and the five childhood companions share a grin as X and Y hand their Mega Rings to Tierno and Shauna.

High up on the Sundial, Essentia keeps herself hidden behind one of the crystalline protrusions, and sees that the kids have let go of their Mega Rings. Although this is clearly a good chance to eliminate those standing in their way, her current mission to hunt down Z the Watcher, whose trail she has tracked to Anistar. The masked trainer is torn between what to do when something suddenly snaps in her helmet's system. Instantly, the person inside the suit, who is Emma, wakes up in confusion, and realizes that she has wandered off to somewhere strange again in her sleep. At that moment, a mechanical voice inside her helmet states that the test subject has awakened and hypnosis shall be activated again, and Emma wonders whose voice it is. She believes that the test subject refers to herself as Xerosic has also called her that, but before she could contemplate any further, she drifts back into slumber and the mechanical voice remarks that transition to artificial intelligence is complete. As soon as the A.I. kicks in, Y shows up on Fletchy, and identifies Essentia as the one behind the attack. The masked trainer automatically activates the suit's evasion system, and pinpoints Y as the target to flee from.

Down below, Tierno hooks the two Mega Rings on his bag strap, and dashes off on his Roller Skates with Shauna on his back…