Oscar Pettinari is a young hick from the suburbs of Rome who drifts around Cinecittà, trying, with mixed luck, to impress acquaintances and producers with tall tales about his imagined stint as a stuntman in Rambo-like action movies. The film opens when he is rejected even as an extra for an American sci-fi production. While bragging to bystanders about his supposed past jobs in the movie industry, the disappointed Oscar Pettinari meets the whimsical lawyer Giangiacomo Pigna Corelli in Selci. The confident lawyer impresses him and inspires him to stage a fake incident, playing the victim of a car crash to pressure the foreign producer into either paying damages or offering him an acting opportunity.
On the appointed day for the simulation, it turns out the producer's car was not driven by him, but by his lead actress and lover, Nancy. The young and beautiful Italo-American actress is dismissed and abandoned by the movie production, faced with money troubles in a country she doesn’t know, while Oscar and the unscrupulous Giangiacomo press her to go along with the ruse—up to the point of arranging unnecessary surgery to squeeze more evidence of the crash out of her. Oscar, however, reveals a surprisingly good-natured side and offers Nancy hospitality at his home, even going into debt to try to keep up with her lavish lifestyle. As they spend more time together, a sense of mutual understanding—and perhaps attraction—begins to bloom between them.
Meanwhile, Oscar grapples with the increasingly eccentric quirks of his lawyer, who pushes him to reject a favorable settlement and to bring the scam to court. In a dramatic moment meant to showcase the spectacle surrounding the case, Giangiacomo faints and appears amnesiac, leaving everyone guessing about what is real and what is not. It becomes clear that the self-styled expert is a mythomaniac with noble origins, prone to episodes in which he convinces himself and others that he truly possesses a particular skill—first a lawyer, then a dentist or veterinarian, and after the last crisis, a ballet choreographer. He is kept safe by his devoted mother and aunt, who seem oblivious to the consequences of his escapades.
Oscar tries to make Giangiacomo recall his promises and commitments, but ultimately he gives up. Nancy finds another path to pursue serious acting in the United States and leaves Oscar without bitterness, perhaps more mature for the experience. Oscar, meanwhile, slips back into his familiar routine, spinning ever more elaborate tales of heroic stuntman feats and auditions in Cinecittà, now playing the part of a cheeky Indiana Jones to keep his dream alive.
