Joseph Gordon-Levitt is coming on board Christopher Nolan's sci-fi action movie Inception for Warner Brothers, joining star Leonardo DiCaprio, according to The Hollywood Reporter.

The top-secret story, which Nolan also wrote, is said to deal with "the architecture of the mind."

Gordon-Levitt is reportedly taking the role to have been played by James Franco, who bowed out over scheduling issues. He would play an associate of DiCaprio's character, a chief-executive type.

Marion Cotillard is already on board as DiCaprio's wife, while Ellen Page is playing a grad student and DiCaprio's sidekick. Cillian Murphy is also in the cast.

Nolan and the studio are aiming for a summer shoot ahead of a 2010 release.

Gordon-Levitt plays the villainous Cobra Commander in Paramount's G. I. Joe: The Rise of Cobra, which opens Aug. 7.