Not What He Seems

The episode opens with Stan working on the Interdimensional Portal. He rigs up some drums with toxic chemicals, as he exclaims on how he does not care how dangerous it is. He sets off a timer and syncs it up with another one on his wrist. As he looks in *Journal 1*, he learns that a side effect of the machine is temporary gravity anomalies.

The next day, Mabel wakes Dipper up to show him a closet full of fireworks. Stan invites them to set them off on the roof. While the twins are playing around, Stan attempts to tell them his secret but fails. As he resolves to tell them the truth later that day, a heavily armored operator proceeds to tackle him, and Agent Trigger comes up behind him to signal the rest of the tactical team to secure the Mystery Shack. Worried and perplexed, Dipper and Mabel inquire what is happening, before they notice Agent Powers and Trigger, whom Dipper thought they had been eaten by zombies. The agents tell the children that an unknown person stole toxic chemicals the night before, and they suspect that the culprit is Stan. They then proceed to put Stan in their car, sending him away to be interrogated. They also take Dipper and Mabel and inform them that they will be going to child services.

Dipper and Mabel decide to clear Stan's name by finding the security tapes from the night before. They force Trigger's car off the road, break out, and head back to the shack. The agents try to interrogate Stan, but Stan insists on his one phone call. Stan uses it to talk to Soos through the walky-talky in his car. He tells him to guard the vending machine with his life. Dipper and Mabel return to the Mystery Shack, and after Dipper nixes Mabel's aggressive initial plan to attack the security forces guarding the front entrance, use Mabel's Grappling Hook to sneak into the attic. They find the security tapes in Stan's office and review the footage. They are able to find video surveillance of Stan restocking the shelves. Seemingly proven innocent, they start to celebrate, when Stan suddenly leaves the shack. They fast forward the footage to see that several hours later, Stan, in full hazmat gear, is the one that stole the chemicals.

After realizing the truth, they find a hidden box in the office full of fake IDs and passports, as well as a newspaper clipping with a headline saying "Stan Pines Dead." Another clipping has a picture of Stan with a caption identifying him as an unnamed grifter. Mabel and Dipper, now totally unsure if Stan is really who they think he is, find a paper with the combination to the vending machine door inside the box. Meanwhile, Stan manages to escape the agents by taking advantage of a gravity anomaly being generated by the machine. After exiting the building, Stan misleads the agents hot in his pursuit by using the cash stolen from an agent's wallet to pay a taxi cab driver to act as a diversion and drive his cab as far away as possible from the Mystery Shack.

When government forces pull out of the Shack to assist in the search for Stan, the way to the vending machine is now clear. The twins head down to punch in the code, when they are stopped by Soos, who has been ordered by Stan to hold the vending machine, with his life if necessary. After a brief struggle, Dipper finally manages to input the code, revealing the secret bunker under the Shack. Inside Mabel, Dipper, and Soos find Stan's secret lab. Upon discovering the other two journals, Dipper is enraged at the fact that Stan has been hiding them and lying to them all summer. He puts the books together to form the blueprints of the machine. He uses his black light to reveal a hidden message by the author. They find out that, if the machine is activated, the entire universe could be destroyed. Dipper then finds out how to engage the manual override.

Right when they're about to hit the override button, Stan shows up begging them not to push it and saying that he will explain. Dipper refuses to believe him, and then another gravity anomaly occurs, lifting everyone up into the air. Mabel makes it to the shut-off button, with Dipper telling her not to trust Stan and push it. Stan begs Mabel to trust him and attempts to approach her only to be restrained by Dipper and Soos. After another fluctuation pins them against a wall, Stan begs her again to not press the button, asking her if she really believes he's a bad guy. Mabel cries at the decision she has to make. Finally, Mabel tearfully decides to trust him and lets herself float away from the override, much to Dipper's dismay.

After the device activates, what seems like an explosion occurs and nearly destroys everything in the Shack. When the light fades, the anomaly shuts down, with everyone seemingly okay, including the main characters. With the portal still functioning amidst the wreckage of the lab, a mysterious man with a rifle over his back walks out of the portal. He places his hand on the first journal, revealing that he is, in fact, the six-fingered man implied to be the author of the journals. Stan reveals that he *is* the author of the journals. The man then removes his hood to reveal he is also Stan's long lost brother, noticeably angry. Mabel asks if someone should be fainting, then Soos replies that he'll faint and proceeds to do so.

In the end credits, Stan and his brother are seen as children, quietly swinging on a swingset on Glass Shard Beach as the sun sets.