An alternate Bellwood erupts into chaos as a mysterious black figure storms through the town’s main street, leaving nothing but wreckage in his wake. Ben Tennyson, in his alien-fire form, Heatblast, steps up to stop him and ends the initial threat with a decisive blow.
The next day at school, [Ben Tennyson] struggles to readjust to ordinary life after the encounter. After a rough day, he endures bullying from Cash and J.T., and even from two girls he had tried to flirt with earlier. In a reckless moment, he inadvertently becomes Grey Matter and unleashes chaos at a diner, only to discover the trouble attracts the attention of his cousin, Gwen Tennyson. The two of them soon confront the same foe Ben defeated earlier, a man named Eon, a member of a time-holding alien species from the Chronian world.
Max Tennyson identifies Eon, noting the Chronians’ history of manipulating time and the Plumbers’ long-ago capture of his race. Eon arrives in a half-dead state with a device called the Hands of Armageddon, a gateway device that could unleash his people on Earth if activated. Max and Gwen guide Ben back to the containment facility, only to find it empty and its guard aged nearly to death. The guard warns that Eon is after the Hands and urges them to keep him from finding the hardware store where they’re kept.
Back in Bellwood, Max, Ben, and Gwen are pursued by Eon as they approach the Hands of Armageddon, guarded by the dwindling Plumbers. Eon breaches the facility but cannot activate the device. When Ben attempts to use the Omnitrix, it malfunctions, glowing a bright purple and wounding him. Eon tries to abduct him, calling it a rescue, but Ben escapes. Eon corners him and explains that his people learned to control time itself, only to be undone by their misuse; he hints that his fate is tied to Ben’s. An elderly Plumber interrupts the moment, and the two exchange warnings about the dangers ahead.
Max suggests that Ben leave Bellwood to avoid capture, but the young hero refuses, and a deal is struck: Ben will be monitored daily by the Plumbers. Later, in the school gym, Eon ambushes him, promising to show Ben a possible future. Ben resists, and transforms into Diamondhead to fight back. He then crafts a trap by leaving himself open, only to be captured along with Gwen and Max when the plan backfires.
Inside the Plumber facility storing the Hands, Eon reveals more rules: the Omnitrix can only keep Ben in an alien form for ten minutes as a safety measure, and he also discloses that he is an evil version of Ben from another timeline, a truth Max had hoped to hide. Deactivating the fail-safe, Eon reduces Ben to a mindless Chronian under his control, powered by a young Chronian to keep the Hands active. Meanwhile, the imprisoned Plumbers, Gwen, and Max stage a daring rescue.
Max sacrifices himself attempting to disable the Hands, while Gwen reaches out to Ben within his Chronian state. Ben returns to himself, and with the help of the Plumbers, defeats the threat, disables the time rift, and banishes Eon back to his dimension. The elder Eon reappears, furious at the outcome, and a final clash ensues where Ben, in the form of [Wildmutt], drives him into the Hands and destroys both the Hands and Eon.
Gwen then accompanies Wildmutt to a school talent show, where a winning moment comes from a clever magic trick that earns them second place. After the show, Grandpa Max suggests giving the Omnitrix a rest for a while, and the trio heads off for pizza, with Ben admitting he will miss the power and the adventures. Yet a thrilling hint remains in the final image: a distant space armada forms, suggesting the return of Vilgax.
