a 10 year old boy named, Zac,and his 9 year old friend Wes finish school for the summer holidays. Their lifes are shown here; They first get into trouble for flying paper airplanes. They then try to stop the local bullies, Cash and JT, beating a kid for his money. Zac,and Wes get beaten up and dangled by their underwear in a tree with the kid. After he helps them getting down, Zac tells his grandfather, Max, how much he has been looking forward to their camping holiday, until he spots his cousin, Gwen (who claims that "someone" persuaded her mother this would be good for her) who he dislikes (apparently because they share the same birthday). When they arrive at the campsite, Zac, Wes and Gwen see that Max wants them to go on a flavor ride which includes eating bugs (they actually decide to work together on saving food for the entire summer).
Zac wanders off into the forest in anger after an argument with Gwen and he notices a shooting star. It hones in on Zac, he just barely jumps out of the way before it hits the ground. He slips into the crater it created. The pod opens to reveal a watch-like object; the Omnitrix. It latches itself onto Zac's wrist, scaring him. After several failed attempts to get it off, the faceplate pops up and shows the silhouette of an alien (Heatblast). Thinking this is cool, he pushes the faceplate back down, and transforms into Heatblast. He screams and runs around in a panic, terrified because he's "on fire", but realizes that he isn't getting hurt, and decides to test his power out, launching several fireballs at the trees... and ends up starting a forest fire.
Wes, Gwen and Max notice the fire, and Gwen grabs a fire extinguisher and rushes to try and put it out, only to find Zac attempting to stomp out the fire(only making it worse, of course). Gwen is terrified at his appearance and, just as he is trying to reason with her, whacks him with the fire extinguisher, sprays him with it, and tells him to stay down. Zac retaliates by lighting her shoe on fire(getting a cheap laugh in the process), and convinces her who he is after insulting her. Gwen asks what happened, and Zac tells the whole story in a matter of seconds, finishing just as Wes, and Max appear. They reveal what happened to Zac, and is just about to tell the whole story to Wes,and Max again, but Gwen interrupts and reminds them of the forest fire. Max tells Zac to start a new fire and let it burn into the old one in order to put them both out; it works, but most of the forest is destroyed.
Zac explains his story to Wes,and Max, still Heatblast. Gwen asks Max if he thinks Zac will stay a "monster", but then Max says he is an alien with a grim expression on his face. This gives weird looks from Heatblast,Wes, and Gwen. Then beeping sounds and Heatblast goes back to Zac. Max says Zac should not mess around with the Omnitrix and he goes to investigate the spot of the crash.
Zac decides to try the Omnitrix again. Wes, and Gwen watches as Zac turns into Wildmutt and Zac discovers his sense of smell by dodging Gwen who was going to hit him with a stick. Zac goes into the woods having fun as Wildmutt. Then his sense of smell detects and jumps, almost hit with a laser. A drone chases Wildmutt until Wildmutt bites the drone. Wildmutt almost defeated it, but then the Omnitrix times out and Zac appears. He is knocked to the ground and is getting targeted with the laser.
Wes, and Gwen appear and does more damage to the drone, destroying it. Max finds the Crash site only to find broken pices of metal and scroch marks and has a bad feeling about it. Max lectures Zac back at the RV. The radio then says about an attack of some sort. Zac realizes it must be a drone. Zac, Wes, Max, and Gwen go near the campsite. Zac turns into Diamondhead. Zac fights the drone while Wes,Max,and Gwen evacuate the area. Zac learns he could reflect the blast and does reflect it, destroying the drone.
The next morning and Wes, Max and Gwen are packing. They wonder where Zac is and he comes as XLR8, saying he had to take care of something. Meanwhile Cash and JT have wedgies in a tree wondering how it happened.
- Zac, goes on a summer trip with his best friend Wes,cousin Gwen,and Grandpa Max.
- The Omnitrix was sent to Earth and locks on Zac's wrist.
- Droids hunt down Zac and the gang to take the Omnitrix.
- Zac transforms into Heatblast, Wildmutt, Diamondhead, and XLR8 for the 1st time