Nemo, Willem Dafoe, is an art thief with a poignant and reflective past. In his storytelling, he recounts a childhood incident where a teacher asked him to select three possessions to save from a house fire. Instead of choosing his family, Nemo picked his beloved cat, an AC/DC record, and his sketchbook. He laments that the cat died, the record was lent to someone who never returned it, but his sketchbook remains—a symbol of his belief that "art is for keeps." This anecdote hints at Nemo's deep connection to art and the importance he places on creation and preservation.
In the present day, Nemo adopts the guise of a handyman to infiltrate a luxurious Manhattan penthouse owned by a wealthy collector. His goal is to steal three works by the renowned artist Egon Schiele, although he struggles to locate Schiele's self-portrait within the lavish space. His daring attempt to steal the artwork triggers a security alarm, trapping him inside the apartment, which then seals itself off completely. As his contacts on the outside abandon him, Nemo finds himself increasingly isolated, facing the challenge of breaking free. The penthouse's malfunctioning thermostat swings between scorching heat and freezing cold, adding to his physical torment. Food and water are scarce—apart from the timed sprinklers in the indoor garden—and Nemo's psychological state begins to waver.
His entry into the apartment is dramatic; after climbing through bird netting over the balcony, a pigeon becomes trapped in the space, slowly starving to death while Nemo helplessly watches. Wasted and injured from repeated escape attempts, Nemo constructs a massive scaffold from furniture in a bid to reach a skylight, which he hopes will lead to his escape. Using improvised tools made from furniture, he gradually dismantles the frame around the skylight, inching closer to freedom. During this ordeal, he becomes obsessively fixated on Jasmine, a young housekeeper he observes via security cameras shown on the apartment's television. Despite the frustration of hearing her nearby while she remains oblivious—wearing earphones and unaware of his desperation—Nemo's desperation grows.
His discovery of a hidden passage in a closet leads him to a private room containing the self-portrait of Schiele and a collection of The Marriage of Heaven and Hell. In his desperation, Nemo turns to consuming the fish from the aquarium and even dog food, which ultimately leads to tooth decay and hallucinations. His physical decline worsens when he falls while removing bolts from the skylight, breaking his leg. Despite patching it up with a splint, his health and sanity continue to erode amid the deteriorating apartment environment.
Throughout his ordeal, Nemo immerses himself in studying the apartment's artwork and creating his own drawings and art pieces on the walls—each a testament to his obsession with creation amid destruction. His attempts to seek help become increasingly desperate; he sets off a smoke alarm, flooding the penthouse in the process, but no aid arrives. In a final act of remorse and reflection, he leaves a message on the walls, recounting his childhood story once more, apologizing for breaking into and damaging his host's home, and affirming that "there is no creation without destruction." He explains that he has saved three pieces of artwork, symbolizing the core of his mission.
The film closes with a serene, lingering shot of the scaffolding now surrounding the open skylight, symbolizing Nemo’s potential escape. Through the skylight, a shadow is visible—suggesting Nemo has finally broken free from his prison, transcending his physical and psychological struggles. This ending leaves viewers with a sense of hope and the enduring power of art as a form of salvation, even in the midst of chaos.
