In a Lego spaceship run by minifigures, astronaut Pee discovers his crewmate El leaving Captain Paranoia's office in clear disappointment. Ignoring Pee's concerns, El wanders the ship, eventually stumbling upon a mysterious rectangular portal. He steps through and finds himself still on the ship, but when he turns around, the portal’s other side opens to a dark tunnel. Eager to know what lies beyond, El goes through again, and the tunnel forcefully pulls him deeper.
El arrives on the far side, in a sprawling maze, where red brick-built creatures appear and conjure a car out of thin air for him. He climbs in, drives through the maze, and the red creatures slip through the portal to board the ship. As El navigates the corridors, he encounters more sentient brick-built beings and a menacing two-headed beast—each head armed with an excavator claw for a mouth—hot on his heels. He frantically tries to escape, narrowly dodging a train, and his car sputters to a halt as he spots the portal once more. He abandons the car, sprints toward the portal, but trips over a loose tire. The beast closes in, devours the car, and charges after the tire, causing El to faint. The beast surges through the portal and into the ship, which momentarily resembles an animation set.
El wakes, reenters the portal, and tells Captain Paranoia what happened. The captain dismisses the tale and shoves El out of his office and into a tangle of live wires. Pee, still intrigued, asks El to lead him to the portal. They search, but the portal is gone. An alarm on the ship blares, rousing Paranoia from a nap; he opens his office door to find the red creatures El encountered earlier phasing through the walls. Paranoia grabs his blaster and hunts for the creatures, only to find the portal right behind him. He steps through and is transported to a blank, featureless space.
On the other side, a plasticine shark fin shadows Paranoia, prompting him to shoot at it until it falls over. The Plasticine, Plasticine, then morphs into various shapes—a wall, a cannon, a toilet tank—to toy with him. Paranoia is flushed through the floor by the Plasticine, which skates through the portal and boards the ship. He discovers the floor is merely a sheet of paper and looks for El and Pee, who are aboard the ship, where the scene resembles an animation set.
Paranoia, now believing El, regroups with El and Pee and returns to the portal with the Plasticine in tow; all three are carried to a desktop. There, the Animator and Pee befriend the Plasticine, while Paranoia tries to shoot it again, only to have El and Pee defend it, convinced it is harmless. They soon realize they are being watched by robots made from screws and bottles of correction fluid. Paranoia leads the trio across the desk in a bid for safety, but the robots close in. The Plasticine saves Paranoia just before he’s shot, and the group is forced to flee as larger machines—now depicted as robots—close in. They find an emergency exit that drops them to the bottom of the desk, where a shoe becomes a makeshift car to outrun the pursuing robots.
The two-headed beast El had escaped earlier reappears, scattering the robots, but resumes the chase. Outside the house, the four hide from the beast and drive toward a shack used by the Animator as an animation space. They coast up a ramp to return to the table, but their disruption wrecks the Animator’s carefully built set. The beast tears through the space and, in its destruction, ends up self-destructing. The Animator, upset, gently returns El, Pee, and Captain Paranoia to their positions, while the Plasticine’s ultimate fate remains undetermined. In a final time-lapse, the Animator repairs the ship, and for a brief moment the red creatures reveal themselves still aboard, with the portal fading into darkness as the scene closes.
