When Grandpa Max's engineer buddy Phil Billings gifts Team Tennyson the Omni-Copter, a state of the art flying vehicle that can transport the Rustbucket for overseas adventures, Steam Smythe takes to the skies to ground Ben and company's first test flight; but unbeknownst to our heroes, Smythe was sent to battle Ben's latest alien forms by a mysterious, powerful enemy: the Forever Knight.
Ben complains about his watch, saying "This is not good". Gwen says that all of the towns that they've been to are starting to look the same. Ben states that they have bigger problems, like his watch not working right. Ben recaps the events of Innervasion, while Gwen denies most bits of the story. Gwen mentions how Max has been acting weird lately(allowing them to play a lot of video games, watching cartoons all day, and allowing them to go to comic shops), but Ben says he won't argue if it means to play more video games.
Ben and Gwen runs into Max who says he has a big surprise for them. Max reminds them of his old buddy Phil, who Gwen and Ben aren't surprised of. Phil tells them that he wasn't the big surprise, and shows them the real surprise. The Omni-Copter. Gwen gets excited about it, and bumps into Ben, which bumps him into Phil's screwdriver, which activated the Omnitrix. Gwen tells Ben that they should use the copter first. Max tells them to settle it over rock paper scissors, and Gwen wins.
Later on, Steam Smythe is seen on his airship waiting for the Tennyson's to arrive. A mysterious voice tells Smythe to be patient, over a radio. Smythe tells the Knight not to underestimate him.
On the copter, Max is impressed by the controls and how it handles. Ben sneaks off to try out one of his aliens. He transforms into Slapback. Gwen catches him, disappointed. Ben tries to find out Slapback's new power. He picks up a crate, which turns out to be too heavy for him. He falls back and Gwen hits his back, accidentally. Duplicating him, both being smaller, heavier, and stronger. The two duplicates have fun with each other, causing the ship to move up and down some. A piece from the airship soon falls on the two duplicates back, creating two more duplicates. This time, all four of them being equally smaller, stronger and heavier. The ship moves up and down again. Max looks back and sees Ben's new alien. Gwen introduces Max and Phil to Ben's new alien. Gwen tells Ben to control his "Slapbacks", which Ben replies saying his name isn't Slapback. Everyone in the ship votes on it. One of the Slapback sides with Gwen, Max, and Phil. One Slapback attacks the other, causing the ship to go out of control, luckily, Max was able to get it steady.
Steam Smythe looks for the Tennysons, impatient for their arrival, when suddenly they appear. The Tennysons manages to get their airship back on it's fly path. Gwen asks have they established why it's a bad idea to play with new aliens on an experimental airship. Slapback comes back together, and reverts back to human. The ship is soon attacked by cannon balls. Ben finds out who it is, and it's revealed to be Steam Smythe. Ben dials up an alien, deciding which new guy wants to go up first. Gwen reminds Ben and he transforms into Cannonbolt. Cannonbolt takes out most of Steam Smythe's creations, and manages to destroy his ship. Ben enters the air ship, and transforms back to human. Ben states how he forgot how awesome Cannonbolt used to be, and Gwen complements Ben's victory. Max looks back asking where should they go, but Phil suggest they set the ship down for a bit, so Phil can finish tuning it up, and so he can remove the cannon balls.
Somewhere else, The Forever Knight states that the Tennysons have only won the day, and soon, night will fall, forever.