At the Monastery of Spinjitzu, Sensei Wu opens a pocket watch just prior to a strange vortex opening in the sky, from which a strange hooded figure emerges. The two quickly recognize each other and soon face off, preparing for battle. Meanwhile, at the Ninjago Museum of History, the ninja are helping put the museum in order after the events of the Day of the Departed. In the process, Kai and Nya discover a portrait of their parents from a number of years previously, just prior to the other Ninja discovering one depicting Wu and Garmadon in battle with two mysterious figures. Dr. Saunders, the museum director, claims that the scene is a fictional battle involving the Elemental Masters, but identifies the two enemies as Krux and Acronix; the latter proves to be none other than Wu's opponent.
As the battle between Wu and his foe, who has traveled through time, commences, Misako is seen at the Temple of Airjitzu, which Ronin is helping her get put together with Dareth "supervises." Upon discovering Nya's Samurai X armor in one of the boxes, Misako feels that it should have been sent to the Samurai X Cave as a keepsake, while Ronin thinks they could sell it and Dareth proposes placing it in a museum or his dojo. Acronix pursues Wu around the monastery ruins, only to end up trapped on a ledge with only Wu keeping him from falling, forcing him to yield; however, a mysterious object then emerges from the vortex and moves time forwards a full minute. Finding themselves aboard the Destiny's Bounty, the Ninja try to determine what has happened, while Misako and her companions are likewise affected.
Now in possession of the object, which he identifies as one of the Time Blades, Acronix renews his battle with Wu, who is on the ropes now that Acronix has the power to move himself forward through time. Acronix then strikes Wu a devastating blow, but before he can finish the battle the Ninja arrive, having identified the monastery as the epicenter of the disturbance that affected them. Though initially outwitted, they are able to coordinate their efforts against Acronix, who tricks them into thinking that he's been defeated before making his escape. The Ninja then find Wu and manage to save him from falling, only to learn that he has to speak to them about their foe, whom P.I.X.A.L. recognized as Acronix. The villain himself then arrives at the museum, where Dr. Saunders reveals himself to be none other than Krux, whom Wu had believed to be destroyed.