Steve Martin is a movie director reminiscent of ED WOOD.
Desperate to produce a movie, he comes up with a plot of covertly filming action star Kit Ramsey (Eddie Murphy) and using the footage for his film Chubby Rain. The covert filming drives a paranoid Murphy over the edge and forces Martin to use the nerdish Jefferson Ramsey (Murphy again) as a double.
The film is almost complete when Ramsey's spiritual adviser (Terrence Stamp) finds out and shuts down production. Fortunately, Martin's illegal alien film crew caught Ramsey on film in a compromising situation with the LA Laker Cheerleaders and the film is released!
Thanks Don P!