Arthur was a dream extractor who worked closely with Dom Cobb to illegally steal information from people's dreams in exchange for money.
He and Cobb were hired by Cobol Enterprises to get a secret from the mind of Saito, a rival businessman. The pair worked with Nash and Tadashi to sedate Saito on a train in Japan and put him under two levels of dreaming. At the bottom level, the Japanese Castle, Dom got to the plans but his ex-wife Mal appeared and took Arthur hostage. They began torturing Arthur, but Dom shot him to wake him in the next level up. Once awake, Arthur gave Dom and Saito the kick and attempted to get the information in that level, but Saito realised he was dreaming and the operation was aborted.
Arthur and Dom escaped the train and went to a hotel. They went to the roof to get out of the country, but Nash betrayed them and Saito was waiting. He told them that he was impressed with their work and wanted them to perform inception on Robert Fischer, who was about to inherit a rival company from his father Maurice Fischer. Arthur believed that inception was impossible but Cobb knew that it was, and agreed to the job.
Cobb found Ariadne,
an architect in Paris, and Arthur taught her the different aspects of dream sharing. He explained to her about totems and showed her the Penrose stairs. Arthur planned out the inception job and researched Fischer, and the team boarded a 747 jet where they were all sedated. In the first level of their dream they kidnapped Fischer on a New York street, but were attacked by his militarised projections. Cobb admonished Arthur for not preparing for a militarised subconscious, but then revealed that if they died in the dream they would drop into limbo. They carried on with their plan and were sedated again in a van driven by Yusuf, and entered the next level of the dream.
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The next level was a hotel, where Arthur explained to Ariadne that Cobb was making Fischer aware that he was dreaming. As such, the projections began to get more host
ile towards the intruders. Arthur tricked Ariadne into kissing him to distract them, but to no effect. Arthur then sedates the rest of the team and sends them to the next level, while the projections attempt to find him. He kills two projections who attack him in the hallway, while on the level above the van flips over causing anti-gravity effects. While the van is in freefall, Arthur puts all the sleeping people into a lift and detonates explosives to send the lift shooting upwards. This kicks them out of their dream, which synchronises with the van hitting the river and waking them all up into the first level again. The inception works and Fischer vows to break up his father's empire, and the team wake up on the plane and enter America.