Four electricians, Dean, [Richard Grieco], Junior, [Jason Jones], Ray, [Richard Yearwood], and Shelly, [Jeff Douglas], are sent to cut the power in a condemned building before it’s torn down. They quickly notice a mismatch between the floor plans and the building’s true size, and when they pry open a door they uncover an old laboratory housing an antique atomic pile feeding a curious machine in the floor. Unwittingly, they trigger an alarm and boot up the device, unleashing a chain of events that changes everything.
Dean, [Richard Grieco], slips through a dimensional portal that appears with the machine, and Junior rushes after him, while Ray and Shelly pore over a journal left by the scientists. The men reappear in a desolate, web-covered Chicago on the far side, and Dean ventures to explore while Junior waits with the others. Shelly, poring over the journal, realizes the researchers were attempting to forge a gateway to a parallel universe, and he and Ray decide to step through as well.
On the other side, no one greets them at first. As Junior bursts out of a broken security van with a stash of money in the back, a sense of relief and confusion washes over the group. Dean returns, armed with a makeshift weapon, but tragedy strikes when Junior staggers forward, a claw lodged in his stomach. The assault of strange, spider-like beings escalates, and a swarm of spider people pours through to attack. A small group of humans fights back, saving the electricians and driving back the creatures, but the battle is far from over.
Back in the unsafe corridor between worlds, the survivors manage to drive to safety and move toward the portal to return home, but Dean halts to help a survivor, and the portal closes, trapping him on the other side. On Shelly’s and Ray’s side, the atomic pile shorts the gateway, forcing Shelly to start repairs while Ray searches for help.
Dean is brought to a hidden shelter where they meet Crane, and a female survivor, Elayna, urges Dean to meet “The Old Man.” She blindfolds him and they set off toward the refuge, as Ray returns with news that most people think he’s gone mad, though he does bring back a small arsenal. Dean finally meets the Old Man, who is Dr. Richard Morelli, the inventor of the portal who found himself stranded thirty years earlier. Dean tells him his friends on the other side are trying to fix the rift, and Morelli warns that when the portal opened decades ago, it allowed a dark force—giant Spider Queens—to slip into this parallel Earth, threatening humanity.
Dr. Morelli explains that the Spider Queen’s venom twists and enslaves people into obedient soldiers, and that survivors are forced to guide the queen’s camps so that others encounter empty, bloodstained outposts. The survivors leave the base with a plan to confront the threat and discover that the Spider Queen has been watching them. Ray and Shelly join the survivors as Morelli and Shelly begin reconstructing a new portal to reach the other side.
The lookout teams spot “soldiers” moving through the buildings, and the group braces for another clash. Dean and Ray defend Shelly and Morelli as they redesign the gateway. The party reassembles to rescue Morelli when they find him in the food chamber, but Shelly has been bitten by the venom and fights to hold them off, gripping Dean’s gun and insisting they go. The four race back to the base while Shelly confronts the Queen, his humanity slipping away under the venom. He tries to shoot the Queen but is too far gone to shoot straight, and he becomes a loyal sentinel for the Queen, guiding her army toward the base. Crane manages to kill most of the Queen’s forces, rescuing Shelly and the Queen from the bulk of the danger, but Crane collapses and Morelli leaves the lab to rush to him. Crane dies in Morelli’s arms, and the Queen descends, killing Morelli in a final, brutal moment.
Shelly makes his way back to the lab and shuts down the power, trying to end the portal. Dean desperately attempts to reach him, but cannot stop the inevitable and is forced to shoot Shelly to prevent the Gate from dragging more souls into its maw. With the portal open, Dean and Elayna race to finish the connection, risking everything as the Queen materializes to block them. The two forge a dangerous final link, and when the last two wires touch, the Queen herself is drawn into the current and electrocuted. The gateway erupts into a massive surge, swallowing the Queen and opening a way back.
Dean and Elayna awaken on a sunlit beach, sharing a kiss as a colossal shadow of a gigantic flying creature looms overhead. It’s ambiguous whether they have landed in a new world or somewhere far removed from their original Earth, and the final fate of their escape remains left to the imagination. The ordeal has left them—and their world—forever altered, caught somewhere between science and a nightmare that refuses to stay contained. The journey is a stark, unsettling odyssey through corridors of power, frontiers of danger, and the uncertain edges of parallel realities.
