Ben Tennyson's secret identity is exposed to the world by an online video, ending his secretive life of heroism. Public opinion on Ben is polarized; he is idolized as a superhero by kids and teens, but distrusted by adults, particularly news anchor Will Harangue, who deems Ben a menace. Ben, Gwen, and Kevin decide to pay a visit to the Internet conspiracy theorist who exposed Ben's identity, revealed to be a ten-year-old boy named Jimmy Jones who runs a website on alien sightings. Not recognizing one of the aliens on Jimmy's website, Ben and his team travel to Orlando, Florida, the site where the photograph was taken, to investigate. Ben's team is brought into custody by the U.S. military, where Air Force Colonel Rozum explains that the alien in question has been stealing parts from a NASA interstellar rocket called Orion. Ben confronts the alien, named Bivalvan, who explains that he is trying to leave Earth after having been stranded there. Ben defeats Bivalvan, who reveals that he is from the Andromeda Galaxy and was kidnapped along with four other aliens by a monster named Aggregor. Ben and his team leave to retrieve the Plumbers, but Bivalvan is recaptured by Aggregor. Later, Ben's classmates take his side and clap for him and the lives he's saved.
Ben's girlfriend Julie Yamamoto has a major tennis match, but Ben is torn between attending and aiding Kevin in stopping the Forever Knights from robbing a museum, while also wanting to watch a new Sumo Slammers movie. Ben eventually turns into Echo Echo and divides into three copies, then returns to his human form so that he can attend all three events at once. However, the split causes Ben's personality to be divided among the trio; while the arrogant Ben attends Julie's match, the kind Ben aids Kevin and the rational Ben watches the movie. Eventually, all three Bens reunite to help defeat the Forever Knights to prevent them from stealing ancient alien battle armor. Ben attempts to reconcile with Julie, but after revealing his actions, she is disgusted with him and storms off.
Ben is approached by video game producer Oliver Thompson, who invites Ben to be the star of his own video game, scanning Ben's alien forms into a computer for motion capture. In reality, however, Oliver is in the employ of Will Harangue, who is developing a battle robot called the Stalker to target and destroy Ben by analyzing and predicting his moves. The Stalker attacks and nearly kills Ben, but Harangue holds back, wishing to exploit Ben's battles with the Stalker for television ratings. He publicly challenges Ben to a final battle at the National Mall in Washington, D.C. Ben is able to defeat the Stalker by using Nanomech, who was too small for the computer to scan; subsequently, Ben uses Way Big to crush the Stalker as well as Harangue's car.
Ben, Gwen, and Kevin defeat an alien rampaging through the streets of Bellwood. Through a universal translator, they learn that the alien, Galapagus, was only trying to get Ben's attention in order to seek his help. Galapagus explains that he was one of the five aliens from the Andromeda Galaxy captured by Aggregor, who brought him into a cell on his spaceship along with the other prisoners: Bivalvan, Ra'ad, P'andor, and Andreas. The aliens manage to escape, but are divided on what action to take: Bivalvan, Ra'ad, and Galapagus send a distress signal out to nearby Plumbers, while P'andor and Andreas confront Aggregor. Aggregor defeats and recaptures them, subsequently killing Magister Prior Gilhil, the Plumber responding to their distress call. Galapagus seemingly betrays the other aliens to Aggregor, but instead turns on Aggregor and helps them flee to a nearby spaceship, which they take to Earth and then go their separate ways. Ben sends Galapagus home via a Plumber ship, but the pilot is revealed to be Aggregor in disguise, who recaptures Galapagus.
Kevin takes on an underground job to open a safe for a large sum of money, only to discover that the employer is P'andor, one of the missing Andromeda aliens, who wishes to be freed from a containment suit that he has been kept in. Kevin refuses to free P'andor after his Plumber's badge detects radiation in the suit; the two battle, but Kevin flees, and P'andor steals a shard of taydenite - the strongest mineral in the galaxy - from him. After Kevin informs Ben and Gwen about P'andor, Gwen insists that they help free him, but Kevin refuses on the basis of him being too dangerous. The trio find and confront P'andor, who attempts to use the taydenite to free himself, but is unsuccessful; he realizes that he needs Kevin to absorb the taydenite in order to free him. P'andor has his minions kidnap Kevin, who taunt him into liberating P'andor, revealing himself as an energy-based alien who absorbs radiation. Ben disguises as Bivalvan and tries to dissuade P'andor from attacking a nuclear power plant, but this only results in a fight. Ben and Kevin ultimately work together to defeat P'andor, who is arrested by the Plumbers. Aggregor then attacks the Plumbers' ship and captures P'andor.
Argit is running a con selling insurance to the Forever Knights, threatening that if they do not pay him, he will destroy their castles. Ben, Gwen, and Kevin investigate and discover that Argit has befriended Andreas, one of the missing Andromeda aliens, and manipulated him into destroying the castles; out of fear, the Forever Knights have now become Argit's servants. Argit is confronted by Sir Dagonet, a legendary Forever Knight seeking to liberate the knights from Argit's influence; he captures Argit, Andreas, Ben, Gwen, and Kevin, intending to execute Andreas using an energy cannon. Ben and the team free Andreas, but Dagonet turns the cannon into a bomb and flees with the knights. On Argit's insistence, Andreas absorbs the bomb's blast, saving the others but seemingly dying in the process. Kevin punches Argit in outrage, and they part ways. Later, Andreas is shown to have survived, and is recaptured by Aggregor.
Ben is attacked in the dead of night by Ra'ad, the last of the Andromeda aliens, but Ben defeats him. Captured in the abandoned military base at Los Soledad, Ra'ad reveals that Aggregor recaptured the other four aliens and blames Ben for it. Ra'ad asserts that the Ultimatrix led Aggregor to the other aliens, and attacks it in an attempt to deactivate it, causing an explosion and vanishing. Ben and his team are subsequently attacked by Aggregor, whom Kevin realizes is an Osmosian - the same species as Kevin's father, and thus possessing the same power to absorb energy that Kevin has. Ben transforms into an Amperi, the species of Ra'ad, and is trapped in his alien form; he realizes that he and Ra'ad are sharing their consciousness. Fleeing from Aggregor to Kevin's garage, Kevin is able to split Ben and Ra'ad, but Ra'ad flees as Aggregor arrives. Aggregor defeats Kevin and Gwen and nearly kills Ben, but Ra'ad intervenes out of guilt and electrocutes Aggregor. Kevin's garage explodes, and Ra'ad is recaptured, but Ben vows to use the powers of the Andromeda aliens to rescue them.
A group of Plumbers ambush Aggregor in an attempt to rescue the Andromeda aliens, but are overwhelmingly defeated. The team then learns from Colonel Rozum that Aggregor has taken the aliens to Los Soledad; Professor Paradox then appears and reveals that Aggregor is using Paradox's technology to facilitate the total absorption of the aliens. Ben and his team confront Aggregor, with Kevin attempting to reason with him, insisting that energy absorption causes Osmosians to lose their sanity. Aggregor asserts that these are merely lies, and absorbs the aliens into himself; the aliens disappear, and Aggregor emerges as a monstrous amalgamation of their forms.
Believing that Aggregor has killed the Andromeda aliens, Ben attacks him viciously, only to learn that Aggregor's new form makes him virtually invulnerable. After Aggregor leaves Earth, Ben and his team are brought to Galvan Prime by Azmuth, who explains that Aggregor's goal is to acquire the Map of Infinity - a complete map of spacetime which will lead him to a mysterious realm known as the Forge of Creation, where he can acquire unlimited power. Because of the map's importance, Professor Paradox separated it into four pieces and hid them throughout the universe in secure locations; Aggregor absorbed the powers of the Andromeda aliens to make him powerful enough to retrieve them. Ben, Gwen, and Kevin travel to the tidally locked planet Mykdl'dy to retrieve the first piece of the Map of Infinity, encountering a group of Necrofriggians and entering an ancient temple. Inside of the temple, the trio evade a series of traps, but end up at the mercy of Aggregor, who takes the piece of the Map of Infinity and leaves. Ben and the others barely escape, resolving to prevent Aggregor from getting any of the other pieces.
Following the events of the previous episode, Azmuth contacts Ben's team and teleports them to the location of the final piece of the Map of Infinity: a huge, cube-shaped structure known as the Perplexahedron, located in another galaxy. The team pursues Aggregor to the interior of the Perplexahedron, discovering that it is an enormous, shifting maze designed by Professor Paradox to protect the final piece of the map from all who are unworthy. Ben eventually deduces a way to navigate the maze, and the trio are able to outmaneuver Aggregor and beat him to the center of the Perplexahedron. There, they meet the Sentinel, an alien who exists to protect the map piece. Ben retrieves the piece, causing the Perplexahedron to begin collapsing; while they try to flee, Ben decides to go back to save the Sentinel. In the process, Ben and Aggregor battle, and Aggregor steals the last piece. The Sentinel, lamenting that all is lost, vanishes in Ben's arms; Ben, resolving to honor him, declares that they will stop Aggregor.
On Galvan Mark II, Azmuth chastises Ben, Gwen, and Kevin for their failure to stop Aggregor from acquiring the completed Map of Infinity. Ben decides to turn into Alien X, his most powerful alien form possessing virtual omnipotence, in the hopes of stopping Aggregor; however, Ben is unable to convince Alien X's split personalities to cooperate, and Professor Paradox ultimately reverts Ben to human form. Paradox explains that the Forge of Creation is the birthplace of Celestialsapiens, the species of Alien X; Aggregor intends to absorb the powers from an infant member of their species, which will give him infinite power. Paradox teleports the team to the Forge of Creation, which is out of sync with time itself due to a chrono-randomization barrier. When Ben falls through the barrier, he accidentally summons a ten-year-old version of himself, who agrees to help them stop Aggregor. In the center of the Forge of Creation, the team battles Aggregor on the palm of a mother Celestialsapien, but all of them are defeated. As a last resort, the ten-year-old Ben convinces Kevin to absorb the Ultimatrix's power, turning him into a monstrous amalgamation of Ben's aliens. Kevin easily defeats Aggregor, but loses his mind and flees. Paradox returns the young Ben to his timeline, while the old Ben resolves to find and rescue Kevin. 153554b96e