The episode starts in the middle of an open field with modern windmills. In the street, Ben's Grandpa Max and Cousin Gwen are semi-conscious inside their overturned RV.
Ben, as "Diamond Head", is fighting Kevin, who is still in his mutated form of combined, Omnitrix, aliens (from an earlier episode). Before Diamond Head can counterattack, Kevin squirts a greenish fluid (using Stink Fly's ability) to distract him. Kevin carries him up to the air, then drops him, knocking one of the windmills down. Diamond Head responds by throwing the windmill blades at Kevin. Realizing that they match each other's powers, they prepare to attack "normally" by running towards each other. Suddenly, a red beam appears from above, enshrouding them, and they seem to disappear. Gwen and Max get out of the RV, and find Ben missing.
In a dark room, the red beam releases Diamond Head, and a spotlight hits him. As he scans the area, an announcer says the "challenger" comes from planet Earth; it seems that he has been transported to a fighting arena complete with a variety of alien spectators. While Diamond Head is distracted by his unfamiliar surroundings and situation, a droid attacks him from behind. The droid has two scythes for appendages. Viewed from overhead, the arena is separated in sections, each containing fighters against a similar droid. Diamond Head is able to destroy one scythe, but the droid is strong enough to crack through his crystalline body. Diamond Head realizes that it's time to become serious, so he slices through the robot's legs, which seems to disable the machine. As the crowd cheers, it seems that someone has been watching his every move.
Meanwhile, Kevin is in the same situation in an adjacent section, and does the same. He uses different powers to defeat the droid. In a flash, he is victorious, and the crowd cheers for him. It seems that the same person has been watching his every move, as well. As Diamond Head gloats, the Omnitrix deactivates, and the audience is surprised by the transformation. The damaged droid is able to get on top of Ben, but Ben is fast enough to use one of the detached scythes to severely puncture and terminate the droid. In an holographic projection overhead, the mysterious being who has been watching them announces his plans to use them for subsequent, staged battles for profit. As the wall between Ben and Kevin opens up, Kevin blames Ben for their current situation, but before Kevin can attack the now-defenseless Ben, they are teleported somewhere else.
Kevin and Ben continue to quarrel, but are stopped by hovering robot guards with stun lances. The robots then attach a device to each of them. Ben and Kevin discover that they are on an intergalactic spaceship, in a room with aliens from various planets, who appear to be in the same situation as themselves. Ben insists they should find a way home, but one alien says that the ship is their home, and there is no way out. Still angry at Ben, Kevin grabs him, but the implanted devices create an electrical discharge between them, forcing Kevin off Ben.
An alarm sounds off, and an alien says that it is meal time. The ceilings open and release a gooey, purple-colored substance. Ben doesn't have the appetite for the alien glop, but the aliens urge him to eat, because "Technorg" will take their food. The sound of heavy footsteps is heard from the background, and a large, orange, alien appears. It is Technorg. As he approaches the aliens, they kneel down to him, while he takes their food. Kevin, still sitting at the table, sneakily uses his "XLR8" tail to throw one of the trays on Technorg's face, and blames the act on Ben. Technorg grabs Ben, and throws him aside. To match his power, Ben transforms to "Four Arms", and returns the attack. Out of view, the mysterious alien continues to watch and be intrigued by Ben's talents.
Ben and Kevin are then transported to another area, where the alien identifies himself as "Slix Thigma", who decides to link Kevin and Ben using an electronic shackle, telling them that what happens to one will happen to the other. Slix then transports them to the arena, where they are to fight Technorg.
As Technorg attacks, Four Arms and Kevin run in opposite directions, forgetting that they are now linked. The mistake allows Technorg to grab a hold of the link and throw both of them down. At that moment, the Omnitrix powers down and Ben is returned to his normal form. Kevin tries to get rid of the once again, helpless Ben, forgetting that if Ben is injured or dies, the same will happen to Kevin. Technorg tries an aerial punch, but Kevin is able to dodge the attack. Kevin then runs away from Technorg, dragging Ben on the arena's dirt floor. Kevin continues to humiliate Ben, but Ben attacks Kevin back by tripping Technorg on top of Kevin. Ben insists that if he and Kevin work together, they can defeat Technorg, but Kevin refuses to accept. Instead, Kevin tries to prove that he can win the battle by himself, by alternately shooting "Stink Fly's" goo and "Diamond Head's" diamond shards at Technorg, which does virtually nothing to the seemingly indestructible Technorg. As Ben finishes his pleas for Kevin's cooperation, Kevin uses "Heat Blast's" fire balls, which explosively ignites Stink Fly's goo. He tells Kevin to try that combination of powers. It works, with Technorg forced off his feet from the explosions. Ben tells Kevin to use a different combination, and with two powerful punches, Technorg is knocked out. Slix orders Kevin to finish him off, but before he can do so, Ben stops him. Kevin continues to fight with Ben, but are stopped by guards. They are given the title of "Champion", and are taken back to the holding cell.
The imprisoned aliens now pay homage to Kevin and Ben. Technorg appears with a tray of food for Ben, who he is honored to serve, not only because he bested him in battle, but for sparing his life, as well. Ben doesn't want to be Technorg's master, and asks if he knows a way off the ship. Technorg says that they have all tried, but it is impossible. As the ship is being prepared to travel to another galaxy, Ben declares that together, they can escape.
A few moments later, as Ben slumps in a corner of the cell, he signals the others to start the plan, and they relay the signal to Kevin who pretends to act out of control. As the robot guards watch, the aliens pile on Kevin, and a flash appears. Ben, now as "Gray Matter" has managed to sneak inside a robot guard, and disable their control devices. Everyone escapes out of the holding cell.
Still linked together, Kevin and Gray Matter try to look for the controls for the emergency escape pods, but Slix is able to track them down, and his drones are well-armed with giant axes. Slix was able to capture the other escapees, and use them as hostages, if they tried to escape again. Kevin and Gray Matter fight the drones to escape and save the aliens from the clutches of Slix, but Ben transforms back into his human form, once again. As the aliens outside are tortured, more robot drones come after Kevin and Ben, who must get to the arena to rescue Technorg from being dropped into a pit of vicious beasts.
Distracted while watching the aliens being tortured, Slix is overcome by Kevin and Ben. Ben insists that Kevin should not destroy Slix, who appears to be an intelligent droid. Kevin, ignoring Ben, is about to destroy Slix, when Ben transforms to "Upgrade" and merges with Slix. Upgrade explains that the droid is actually the main command center for the entire ship. He then finds the control console, and breaks their electric shackle link. As Technorg falls from the platform, Upgrade sends a flying platform to catch him. Slix seems able to regain some of his control, but before he can peel Upgrade off, Technorg knocks him out. Upgrade then teleports the imprisoned aliens and themselves to the escape pods.
As Upgrade activates the escape pod doors, every alien escapes successfully, but Technorg insists on staying with Ben. Upgrade pushes him into the pod. Just as he is ready to leave, the Omnitrix deactivates, revealing Slix Thigma as a robot, grabbing Ben to destroy him. Kevin destroys Slix, saying that he wanted the fun of hurting Ben, himself. He hurls Ben against a wall, and, using Stink Fly's goo, attaches him there. Ben tries desperately to activate the Omnitrix, and, just in time, he changes into Cannon Bolt. Kevin is surprised by the new-to-him alien form. Cannon Bolt bounces off the walls battering Kevin to the floor. He then enters a pod to escape, but Kevin holds the door open, but is stopped by Technorg who has returned to the ship to defend Ben. Ben says they are now even, and as he jettisons off the ship in his escape pod, Kevin feigns a meek smile as Technorg approaches, presumably to bash him for his treachery. The ship, having been previously programmed by Slix, disappears into hyperspace, sending Kevin and Technorg far away.
The escape pod lands on Earth, and Ben tumbles out as himself, apparently overcome by the shock of the rocket travel. Gwen and Grandpa have left the damaged RV and seem no worse for wear. They are glad to see that Ben is okay, as he is them. Gwen asks where Kevin is, and the episode ends with Ben saying that Kevin has found a new "playmate", and that they probably won't be seeing him for a while.