After Billy Billions' efforts to carve his face onto Mount Rushmore with a laser are thwarted by Ben, the billionaire brat turns his focus on removing Ben from the Omnitrix, but once he accidentally rips open a rift in space-time, the two must carefully navigate another timeline if they are to return to the present.
Ben and Billy fight each other in a forest near Mount Rushmore. Ben transforms into XLR8 and Billy tries to blast him. XLR8 gets hit by Billy's ray and it generated some kind of portal, Ben gets sucked into it with Billy. Ben falls out of the portal, and lands in a place he's not sure of, he then hears Gwen calling Ben to find some firewood. XLR8 runs near Gwen, and Gwen freaks out, as she thought Ben was a monster. Meanwhile, Billy was someone near Ben and Gwen, and because Gwen thought Ben was a monster, he can finally continue his plan. Billy bumps into past Ben while running. Past Ben didn't really recognize Billy, however, Billy figured he time travelled back to the past. He then distracts past Ben with his laser helmet.
Ben times out and turned back human, because Gwen thought Ben was a monster, he thinks Gwen is messing with him and reminded her about the Omnitrix. Suddenly, the Omnitrix starts disappearing. Ben attempts to look for it. Billy, distracting past ben, sees the Omnitrix pod. Ben notices the Omnitrix crash as well, and takes Gwen to the Omnitrix crash site. However, Billy was there first. Billy then explains that him and Ben time travelled to the past. Billy takes the Omnitrix. He uses it to turn into Four Arms and attacks Ben and Gwen, but they managed to escape. Ben leads Billy to the alien drones that were searching for the Omnitrix. Billy is then chased by the alien drones. The three found the portal and entered it.
They got out of the portal again but this time, it appears that they are wearing medieval outfit with Billy being 'the king'. Gwen states that the universe couldn't handle Billy being the king anymore. Ben and Billy spots the pod crashing, and runs towards it. However, a squirrel gets it. They jump through another portal, this time having their regulars appearance. The pod falls again, and Ben and Billy runs towards it. Max walks through the forest, and Gwen questions what he's doing. Max tells her that he's going fishing. Ben returns, as Four Arms, holding Billy. Another portal opens up, and the drones return. They all jump through the portal.
They return through the portal, this time gaining a futuristic like appearance. Ben questions what keeps happening. Gwen explains that the space-time continuum keeps collapsing, and something is still wrong, and the timeline can only sustain the mistake for so long. Gwen questions the logic of them traveling time due to XLR8 being shot with a laser. Ben suggests it has something to do with XLR8 being fast. Gwen asks why didn't it stop when he got back the Omnitrix. Ben isn't sure, since they also get the watch, but every time, the past never goes back to the way it was, no matter who has the Omnitrix. Gwen thinks, figuring that maybe Ben isn't supposed to get the Omnitrix. Ben is confused on what she means. Gwen explains that his past counterpart should get the Omnitrix, and if he finds it, the timeline should go back to normal. They arrive at the crash site, and Billy attacks with his robotic suit. Ben fights him off, and Gwen looks towards the Omnitrix, getting an idea. Ben struggles to fight off Billy. Gwen uses the Omnitrix, and transforms into Four Arms. She attacks Billy, and they fall through the portal. Coming through, they gain pirate-like appearances. Billy runs off to find the Omnitrix, and Ben follows. Gwen runs to find her Ben. She finds Past Bn. Past Ben fascinates over her appearance. One of the drones retrieves the Omnitrix, but Ben and Billy tries to take it back. They then take it, and fights over it. Past Ben is confused to why he's fighting Billy. Gwen explains that he needs to put the watch on. Future Ben throws the watch to past Ben. The watch slaps onto past Ben's arm, and Billy and Ben fades away. Gwen begins to fade away, but she tells Ben not to transform into the fast alien, when he fights Billy Billions. Ben didn't understand a thing, but Gwen fades away, and past ben hits his watch.
In the present, Ben fights Billy again, this time, transforming into Four Arms.
Ben revisits the location he found the Omnitrix.
The circumstances of Ben finding the Omnitrix are shown for the first time.
However, these events are altered by Ben, Billy, and Gwen as they changed the original timeline.
Gwen, Billy, and a Squirrel all gain the Omnitrix in alternate aborted timelines.