A fictionalized account of famous French writer Emile Zola and his involvement in the Dreyfus Affair. After struggling to establish himself, Zola wins success writing about the unsavory side of Paris and settles into a comfortable upper-class life. However, Zola's complacency is shaken when Jewish officer Alfred Dreyfus is imprisoned for being a spy. Realizing that Dreyfus is an innocent victim of anti-Semitism, Zola boldly pens a newspaper article exposing the truth, is charged with libel and must defend himself in a dramatic courtroom testimony.

France, 1897. Colonel Georges Picquart challenges the French government when he discovers the obscure political maneuvers that led to the imprisonment of the Jewish Captain Alfred Dreyfus after being convicted of espionage in 1894.

Amid a tense political climate, the opposition leader is killed in an apparent accident. When a prosecutor smells a cover-up, witnesses get targeted. A thinly veiled dramatization of the assassination of Greek politician Grigoris Lambrakis and its aftermath, “Z” captures the outrage at the US-backed junta that ruled Greece at the time of its release.

Victim of a terrible plot, Captain Dreyfus was sentenced in December 1894 to deportation for high treason. His wife Lucie made a pact with him: to live, whatever the cost, while awaiting rehabilitation. During five years, the Dreyfus spouses exchanged hundreds of letters. They became a weapon of survival for Alfred. This film is the story of the correspondence of a man and a woman who unwittingly became the unsung heroes of the case that bears their name.