The episode starts off with the Defenders running towards the monastery, which is currently under attack. They hurry to the entrance, hoping that they're not too late to retrieve the Key.
At Brackus' Keep, Flinch reports through a projection that he and Malco have reached the monastery, but that they haven't found the Key yet. Brackus gets angry and orders them to kill the Di-Gata Defenders if they get in the way.
Back outside, Seth prepares his team for attack, but the anteater creature they met earlier has a better idea. He leads the Defenders to another entrance, which is actually an elevator that Erik activates. He, Kara and Melosa are impressed at such advanced technology, but Seth doesn't share their amazement. He starts to feel sick and sits down while clenching his stomach in pain.
In the swamp, Adam is calling out for Mel. However, the three Toads he encountered earlier answer instead of the young girl. They threaten to kill him because he didn't listen to their warning, but Adam starts sweet talking to get out of trouble. He wants to make things right again with Mel, but he needs the Nova Stone to do that. The trio refuses to give him back their payment, but Adam uses his thief's cloak, which can make him invisible, in order to steal it back. He defeats the Toads and recovers the powerful Stone.
As for Seth, his stomach ache isn't getting any better. It's only when the elevator comes to a stop that he finally retrieves his senses. Erik and Mel find an opening in the wall small enough for both of them to see what is happening on the other side without being detected. Flinch is trying to find the Key and asks the monks where they hid it. Unable to get the information out of them, he moves on and leaves Malco to deal with the pacifists. The Defenders immediately understand that the Order of Infinis is back, and so they plan to find the Key first and get out without being caught.
Flinch is getting annoyed at the monks' persistence and decides to search for the Key himself. He traps the pacifists under a force field and leaves the room with Malco. Seth jumps on the occasion and runs out of the elevator, followed by the others. Mel and Erik are charged of freeing and taking the monks to safety while he and Kara go find the head priestess in order to get to the Key. As the group separates, Melosa is attracted to a mural with a carved character that feels familiar to her. Flinch interrupts her deep thoughts and prepares to attack when Adam comes once again to the rescue. He explains that he wants to apologize for what happened in the swamp, and Mel is interested. Flinch takes this opportunity to call his guardian, Dreadcrow. Melosa and Adam start fighting on whether she or he can handle it. The evil scientist gets annoyed, but takes the occasion to escape by the window. Finally, Adam tells Melosa that Flinch is all hers.
Somewhere else in the monastery, Seth and Kara are still in search of the priestess who seems to have vanished. Such is not the case since she magically appears from the shadows and leads the two to the Key, unaware that Malco has followed them. To make matters worse, Flinch comes by the window and traps them under an energy dome that neutralizes their Di-Gata energy along with Kara's power boots that enable her to walk. Flinch immediately gets to work regarding the force field protecting the Key, but Malco has a more simple idea: punch it until it breaks. Erik comes at that moment and lures Flinch out of the room with his guardian Robotus in his mini form. The young inventor pretends to be amazed of the scientist's booster cell transformed into a portable Di-Gata powered operating system, which distracts the evil doer. Robotus takes this opportunity to insert a Stone in the cell, creating a booster surge that electrocutes Flinch. Erik then deactivates the shield imprisoning Seth, Kara and the priestess. Now back in business, the three Defenders prepare to attack Malco who managed to break the Key's force field. Mel arrives and joins the fight while Adam is forced to stay out of the way.
As the battle begins, the Defenders realize that Malco has a special ability: his shields, equivalent to ten Shield Stones, are permanently bonded to him. They try to fight anyways, but their attacks are no match for Malco's destructive power. Seth calls the Warrior Henge, but even that isn't enough to defeat the giant. Kara suggests using the Nova Stone, but Seth doesn't have it anymore. Adam hurries to give it back, and the power of the Nova Stone is finally released. It creates a giant explosion that defeats Malco and destroys half the monastery. Seth realizes that he's not ready for this kind of power, just like Professor Alnar had told him. He then turns to Adam, ready to jump at his throat for stealing his Stone, but Mel intercepts the two. She wants to give the thief another chance.
Their attention is next directed to the Key, which is in Flinch's hands. Coward as always, the scientist refuses to fight and destroys the Key so no one can have it. The Defenders are ready to run after him, but the priestess prevents it. The real Key was hiding in her staff from the very beginning, so there's no need to continue the battle. She offers to speak with Alnar and places the professor's Life Stone in a machine that grants him the power to take form. He congratulates the Defenders and officially declares that their journey has started.
Meanwhile, Flinch makes his report to Lord Brackus who is angered of the scientist's incompetence. He ends the conversation and meets with Lord Nazmul who is also angered. The founder of the Order of Infinis says that he will be the only one to rule over Rados, and Brackus agrees with a respective bow. The episode ends on a close-up of Nazmul's evil eyes.