As Annie departs for the weekend, Dave plunges into his latest artistic project, propelled by an unrelenting creative impulse. Despite a history of abandoning ideas midway and depending on his parents for financial aid, Dave experiences a breakthrough as he intricately crafts a cardboard fortress from the inside out. When Annie returns, she is taken aback by the seemingly mundane fort that conceals extraordinary attributes. As she timidly shakes the exterior, the multitude of machinery and sounds emanating from within sparks her curiosity.
Annie reaches out to Gordon, who invites their group of friends—Leonard, Brynn, Greg, Jane, and Harry, an adventurous filmmaker along with his boom operator and cameraman—for an impromptu visit. They are joined by a homeless man, recruited for his expertise in cardboard, and two unexpected Flemish tourists who bring an air of intrigue. As the friends gather at the apartment, Leonard’s initial enthusiasm wanes when he realizes that entering the fort is impossible. Meanwhile, Harry identifies an opportunity to document Annie’s genuine feelings for Dave and decides to venture into the maze with the others.
As they journey deeper into the labyrinth, Annie, Gordon, Harry, and his crew uncover a realm of surreal marvels and supernatural wonders. They traverse rooms alive with origami birds and other fantastical beings, gradually shifting from awe to a profound appreciation for Dave's creation. Meanwhile, Leonard lingers in the background, and the Flemish tourists seem engrossed in their own little world, picnicking amidst the cardboard curiosities.
Navigating the increasingly perilous maze, the group encounters Jane, whose unexpected demise at the hands of an ax-wielding Minotaur leads to a bizarre and confetti-filled conclusion. In the chaos, Greg's ill-considered attempt to disable a trap results in his gruesome disappearance, compelling his friends to confront the reality of the Minotaur's sinister forces.
As they delve further into the labyrinth's depths, Annie’s ingenuity uncovers a startling truth: the maze itself is alive, its walls throbbing with a mysterious energy. The group’s shock escalates into horror when the Minotaur seizes Brynn, plunging them into despair.
Their desperate quest takes an unsettling twist when they encounter Dave, who bears cryptic warnings that only deepen the maze's mystery. As they navigate through the treacherous turns, they come across Dave’s own strange affliction: his hand has morphed into a cardboard contraption—a peculiar side effect of his prior experimentation with the labyrinth's hidden vulnerabilities.
As tensions rise and the situation grows dire, the friends become convinced that their best chance of escaping lies in attacking the maze’s core. While Dave hesitates, Annie's unwavering resolve drives them forward, leading them to a surreal and disturbing revelation: a cardboard puppet version of Brynn, trapped in an endless loop of begging for high-fives.
Meanwhile, Gordon, Harry, and the crew become entranced by the puppet's antics, obliviously distracted from the maze's true nature. As Dave and Annie approach the heart of the labyrinth, they stumble upon a strange zoetrope-like creation that seems to capture the very essence of the maze.
Their progress catalyzes a cascade of surreal and horrifying events: the puppet version of Brynn triggers a demonic hand that drags the cameraman into chaos. As Harry clings to a bag of tapes, he finds himself falling prey to the whims of the labyrinth. In the midst of this madness, they must confront the true horror of their predicament: a living, breathing maze that ensnares them in its grip unless they can unravel its secrets and navigate its deadly traps.
When the group regroups, Gordon smartly diverts the Minotaur’s attention, affording the others a chance to strategize. However, tragedy strikes as Leonard falls victim to a gruesome fate, taken out by seemingly innocuous cardboard saw blades. With the Minotaur briefly distracted, Dave, Annie, Harry, and the boom operator seize the moment, positioning themselves for a final assault on the maze’s heart. Armed with a razor-sharp katana, they deliver a decisive strike that sends the walls crashing down. When the dust settles, the group finds themselves back in their apartment, surrounded by the remnants of their cardboard creations. Harry promptly turns to Gordon, entrusting him with the grave responsibility of informing the families of the fallen. Meanwhile, Dave becomes engrossed in brainstorming a title for their documentary, leading Annie to sarcastically suggest, "Dave Made a Maze," despite Gordon's insistence that it should be called a labyrinth.
As they finish clearing away the last of the cardboard debris and tossing it into the dumpster, Dave and Annie are oblivious to the Minotaur emerging from the wreckage, accompanied by an origami bird. The creature ambles away, holding a mysterious "I Love You" sign, leaving the group to contemplate the surreal and baffling nature of their adventure.
