“Goya’s Ghosts,” the new feature from the director Milos Forman (“Amadeus,” “Man on the Moon”), is an unwieldy mix of political satire and lavish period soap opera. Set in 18th-century Spain, and covering the last phase of the Inquisition and Napoleon’s occupation, it resembles the Oscar-baiting epics that Miramax used to release: white elephants like “Chocolat” and “The Cider House Rules” that mixed art-house swagger, Hollywood glitz and shout-outs to liberal common wisdom.

The tale begins with Spanish church elders condemning etchings by Goya that depict the torture of dissidents and heretics. “These images show us the true face of our country,” frets Brother Lorenzo (Javier Bardem), a quasiliberal monk who has asked Goya (Stellan Skarsgard) to paint his portrait, but also exhorts the Roman Catholic Church to fortify the Inquisition and purify the country.

Mr. Forman and his co-writer, Jean-Claude Carrière (once a frequent collaborator with Luis Buñuel), depict Goya as an artist trying to balance the need to make a living against the obligation to document atrocities committed in the name of God and war. (When Napoleon invades Spain in the film’s second half, Goya again becomes a witness to history.)

But Goya’s presence in the film recedes after he asks Brother Lorenzo to investigate the disappearance of one of his models, Ines, (Natalie Portman, likable but bland), the daughter of a rich merchant.

Ines is being held incommunicado for the crime of having a Jewish ancestor. The sequence depicting church interrogators grilling her about a recent supper (she’s said to have refused pork) balances satire and terror with precision. (The hard cut from Ines politely asking questioners what she can do to prove her honesty to a naked, screaming Ines hanging upside-down from a rack is an early candidate for transition of the year.)

Equally bracing is a sequence in which Lorenzo, after forcing himself on Ines in prison, has dinner with her family and lamely tries to reassure them that if Ines truly loved God, no amount of pain would make her sign a false confession. Ines’s family disproves Lorenzo’s claim with a panache that Charles Bronson would have appreciated.

By recreating Inquisition brutality, “Goya’s Ghosts” aims to denounce the West’s bludgeoning response to terrorism. But its rhetorical tactics are jejune; its comparison of 21st-century America and Inquisition-era Spain doesn’t track; and its second half abandons satire for half-baked historical melodrama.

Mr. Bardem’s portrayal of the newly enlightened Lorenzo — who tries to help Ines find the daughter they had together when she was a captive — is filled with fine brush strokes that make the character compelling, if not quite comprehensible. But the sight of Ms. Portman playing both Ines and her daughter, Alicia — a grimy prostitute — is alternately distracting and laughable.

Randy Quaid’s supporting turn as the dimwit thug King Carlos IV is an inferior rehash of Jeffrey Jones’s peerless work as Emperor Joseph II in “Amadeus.” And the film’s stumblebum attempts to transform the opportunistic hypocrite-rapist Lorenzo into yet another of the director’s martyred rebel heroes — each noble gesture backed by an “Applaud now!” score — is auteurism run amok.