Eames is an essential part of the secrecy and deceit within the dream world. Eames can project the image of anyone, essentially forging an identity as a literal physical manifestation. Combined with his ability to mirror other people's mannerisms and behaviors, he is a very capable doppelganger. This skill comes in handy, and can help convince another person that whomever team needs him to be in order to aid their deception.
During the events of Inception, Dom Cobb recruits Eames as the team's forger, sensing the need for thief with Eames' specific talents and capabilities. After meeting Cobb in Mombassa, Eames agrees to the request and introduces Cobb to Yusuf, a chemist who can tailor compounds to the particular needs required to accomplish an inception. In preparation for the job, Eames closely observes the behaviors and mannerisms of Peter Browning, the godfather of Robert Fischer, the mark for the inception job. In imitating Browning, the Inception team intends for Eames to gradually persuade Fischer into believing his father, Maurice Fischer, had intended for Robert to dissolve his father's company and build something for himself.
During the first level of the dream within the dream within the dream, Eames and his colleagues are furious to learn that because of the level of sedation required to stabilize the multiple dream levels that death, which would ordinarily wake the dreamer up, will actually cause them to fall into Limbo, a dangerous location where a dream has no limitations including the perception of what is reality. However, in order to avoid Limbo, the team is forced to finish the job as quickly as they can. Eames, as Browning, successfully suggests to Fischer in the first level that his father had wanted Fischer to create something for himself.
In the subsequent level, a hotel dreamed by Arthur, Eames transforms into an attractive woman to serve as a distraction to Fischer so that Cobb can pull off a risky tactic of revealing to Fischer that he is dreaming, without turning Fischer's subconscious against them. During the next level of the job, a snowy mountain in a level dreamed by Eames, the forger is tasked with distract Fischer's militarized subconscious while the rest of the team guides Fischer to a hospital where the inception should take place. Though the attempt appears to have failed when Cobb's subconscious projection of his wife, Mal kills Fischer, Ariadne suggests that she and Cobb go to Limbo to find Fischer and send him back to the third level, where Eames must resuscitate him so that Fischer can enter a strongroom where his subconscious will reveal if he has accepted the planted idea. Ariadne's plan succeeds and Eames blows up the hospital in order to wake everyone on the level up in the previous level, where Arthur detonates everyone in a hotel elevator, as the van driven by Yusuf, in the first level hits the water after falling off a bridge.