True story of writer Emile Zola's defense of Alfred Dreyfus, a Jewish army officer framed by anti-Semites.

In early 1890s Paris, army officer Maj. Ferdinand Esterhazy requests a private meeting with the German embassy attaché, Maximilian von Schwarzkoppen, offering to sell him French military secrets. Suspicious, von Schwarzkoppen initially rejects the offer and carelessly throws Esterhazy's list of military documents in his office trashcan where it is later retrieved by an undercover French agent. Sometime later, War Minister Gen. Auguste Mercier meets with several high-ranking staff officers to announce that several vital defense plans have been stolen from headquarters. Shortly after an internal investigation begins, Esterhazy pressures his friend, Maj. Hubert Henry of counter-intelligence, to expedite his transfer request. Later, the head of espionage, Col. Jean Sandherr, shows Henry part of an intercepted note from the German to the Italian attaché mentioning a contact known by the initial "D." Sandherr also reveals that the intercept also produced a letter to the German embassy from the presumed French spy. In examining the list of the staff officers, the men pause over the name of Capt. Alfred Dreyfus, a hard-working, solemn officer and the only Jew on the General Staff. Sandherr summons handwriting expert Maj. Du Paty de Clam to examine the letter. The following day Du Paty and Henry meet with Sandherr and Dreyfus' commander, Maj. Georges Picquart, who is startled to learn that the men suspect Dreyfus. Later, Dreyfus is summoned to meet Du Paty and, without explanation, ordered to write several lines. Upon examining Dreyfus' handwriting, Du Paty arrests Dreyfus. Bewildered, then angered, Dreyfus declares that he is innocent of any wrongdoing, but is taken into custody. After Dreyfus' house is searched, his wife Lucie and brother Mathieu demand to see Dreyfus, but Sandherr insists that he must remain in solitary confinement. Sandherr then warns Lucie and Mathieu not to speak with the press, cautioning them that the public would respond violently to news of treason. Shortly thereafter, Esterhazy returns from a trip out of town and learns of Dreyfus' arrest and pending court-martial. After secretly meeting with von Schwarzkoppen to assure him that he is not a suspect, Esterhazy visits a local newspaper editor to reveal Dreyfus' arrest, insisting that he is motivated out of a sense of patriotic duty. Civilian attorney Edgar Demange offers his services to defend Dreyfus. As the court-martial looms, Picquart warns the War Minister that the General Staff will look foolish if Dreyfus is not found guilty, but Sandherr insists that the "proper" verdict will be reached. At Mercier's insistence, the military trial is held in a closed court. Du Paty and several of the officers give evidence linking Dreyfus to the note and suggesting sinister motives for his aloof behavior. Henry then stuns the court by testifying under oath that a trustworthy source informed him of a spy within the General Staff and identified the traitor as Dreyfus. When Demange insists that Henry reveal his source's identity, Henry refuses and the judge supports the refusal as necessary for the defense of national intelligence. Dreyfus is found guilty, prompting him to attempt suicide in his prison cell. When Mercier requests Dreyfus make a confession of guilt, however, he refuses and is sentenced to life imprisonment on the notorious Devil's Island in French Guiana. Picquart then receives an intercepted note from Esterhazy to the German Embassy, and recognizing the writing, compares it to the original letter used against Dreyfus. When the writing matches, Picquart reports the discovery to Mercier, who nevertheless refuses to reopen the Dreyfus case. Mercier then orders Picquart transferred to Tunisia. Unwilling to disgrace the army, Picquart drops the issue and leaves the evidence with his lawyer, Louis LeBlanc. Before leaving for prison, Dreyfus is publicly humiliated by the Army in front of a cheering throng. On Mercier's orders, Dreyfus is held in isolation, chained to his bed every night and is not allowed to read Lucie's daily letters. A year after the conviction, in order to keep interest in the case alive, Mathieu prints phony fliers declaring that Dreyfus has escaped and fled to England. The flyer attracts LeBlanc's attention and he summons Lucie and Mathieu to show them the evidence exonerating Dreyfus. The evidence eventually results in Esterhazy's court-martial, but the judge refuses to hear testimony regarding Dreyfus, as the case is closed. Esterhazy is subsequently acquitted and Picquart, who has returned to testify, is arrested. Outraged by the verdict, famed novelist Émile Zola and politician and publisher Georges Clemenceau offer their services to Lucie and Mathieu. Zola then writes an open letter to the president, calling Dreyfus' verdict a national shame and accusing Mercier, Du Paty, Henry and Sandherr of willfully concealing evidence motivated in part by anti-Semitism. Clemenceau publishes the letter in his newspaper under the banner: "I Accuse." The letter prompts international attention to the Dreyfus case and the president then demands Dreyfus be returned from Devil's Island to face a new, legitimate trial. Mercier furiously defends the military justice of the first trial, insisting that the army cannot appear weak or divided to the nation. Five years after his conviction, a stunned and aged Dreyfus is returned to France for a second trial. Picquart, now a civilian, testifies for Dreyfus. To the cheers of the army, a livid Mercier testifies against Dreyfus, brushing aside evidence that Henry forged letters and that Mercier himself swayed the opinion of the judge in the first trial. At the trial's end, Demange informs Dreyfus that although it is certain he will be found guilty again, the president has assured him a pardon. Zola and Clemenceau plead with Dreyfus to reject the pardon, which would mean accepting the guilty verdict, but exhausted and unable to face returning to Devil's Island, Dreyfus accepts. Over the next two years, Dreyfus' name continues to provoke controversy throughout France and Dreyfus wonders if he will ever find peace. Some years later in London, Esterhazy, in need of money, shows his memoirs to a publisher, which results in Dreyfus' complete exoneration. Picquart and Dreyfus are reinstated into the army and Dreyfus is publicly presented with the Legion of Honor as Lucie, their children and Mathieu look on.