Eric and Dodd are tasked with recording the dreams of Cassandra Rains. In her dream, Eric is taken captive while walking in a forest with his daughter Anna. Upon awakening, Cassandra encounters others in the Cube. One man, Robert Haskell, bears a tattoo resembling that of the soldier who captured her, yet he, like the rest, has no memory of his past. Eric suspects everyone in the Cube is on death row and must decide between entering the Cube with erased memories or facing execution.
The story focuses on Cube technician Eric Wynn and a woman named Cassandra Rains, who is trapped in the Cube. It kicks off with Ryjkin’s failed escape attempt, resulting in his body disintegrating after being sprayed with what he thought was water. Eric witnesses this alongside his colleague Dodd. Later, Eric sketches Dodd while playing chess, paying no attention to the game. Following his victory, he questions their missing colleagues, but Dodd warns him against probing too deeply into the Cube.
Entry necessitates signing a consent form, which Eric notices Cassandra lacks, prompting him to clash with Dodd to inform their superiors. As he readies to contact them, the phone rings. They are instructed to initiate ‘escape procedures’ for a subject at the Cube’s exit undergoing a final test. This individual turns out to be Owen, a former coworker. When asked if he believes in God and responding negatively, he is instantly incinerated. Eric disputes this outcome with Dodd. Recognizing the Cube’s malevolence, Eric decides to enter it to aid Cassandra’s escape.
Jax, a supervisor, and two analysts arrive in the control room to obstruct Eric from assisting Cassandra. Despite their efforts, Eric and Cassandra make it to the escape room, with Dodd’s help who sabotages the Cube’s controls and pays for it with his life at the hands of Jax. The sabotage triggers the Cube’s ‘reset mode,’ which vaporizes any living beings inside after a certain period. Eric and Cassandra escape the ‘escape room’ through a concealed exit, but they are intercepted by soldiers. Cassandra manages to flee, but Eric is subdued with a dart and loses consciousness.
He awakens in an operating room to Jax, who informs him that while Cassandra may have eluded capture, Eric has been charged with ‘treason’ and ‘sabotage’ against his country and God. He is sentenced to ‘two lifetimes’ with a brain microchip to be implanted. Jax asserts that Eric was put on trial and presents him with a consent form, indicating he was an observer in the Cube. Eric dreams of Cassandra reuniting with her daughter and hailing him as a ‘superhero.’ Ultimately, Eric undergoes a lobotomy to erase his intellect, and he is ultimately seen in the Cube with other victims of government experiments.