The year is 1792, and a bloodthirsty revolution has taken hold of France. In Paris, common citizens watch daily as hundreds of aristocrats and nobles are beheaded by Madame Guillotine. Barricades surround the city in order to keep aristocrats, who are in hiding, from escaping the city.
Sergeant Bibot and his men guard the West Gate, watching for fugitives. Bibot prides himself in being able to spot the feeble disguises of France's former elite. People gather at the gate to see whom he'll catch and return for judgment.
Lately, however, a band of Englishmen, led by an enigmatic figure calling himself the "Scarlet Pimpernel," has managed to guide many aristocrats to England and freedom. Bibot brags that he will not be fooled. He carefully scrutinizes each passing cart until one old hag tells him her grandson, who lies in back, has small pox. Bibot hurriedly lets the cart through without further inspection.
Minutes later, the captain of the guard arrives and demands to know if an old hag has passed; the cart contained the Comtesse de Tourney and her two grown children, all condemned to die as traitors. The old hag was none other than the Scarlet Pimpernel.
The Comtesse de Tourney and her children are guided to The Fishermen's Rest, a small inn in Dover, by Sir Andrew Ffoulkes, a subordinate of the Scarlet Pimpernel. They are greeted by the staff and Lord Antony Dewhurst, another co-conspirator. At dinner, it is obvious that Sir Andrew is attracted to the Comtesse de Tourney's daughter, Suzanne.
The talk at dinner centers around the family's daring escape. The Comtesse mentions that some people are betraying families to the revolutionaries. One woman in particular, Marguerite St. Just, decried the Comtesse's cousin to the police. He and all his family were beheaded. The Comtesse prays she will never meet that woman again.
Lord Antony and Sir Andrew are visibly upset at this news. Marguerite St. Just has married Sir Percy Blakeney, one of the most highly respected men in England. The couple is considered to be the most fashionable in society, and they are close friends with the Prince of Wales.
At that moment, Lord and Lady Blakeney arrive at the inn to stay the night. The Comtesse de Tourney forbids her daughter to speak to Marguerite, even though the two were once close friends. Lady Blakeney dismisses the slight with cold sarcasm.
Sir Percy Blakeney is an English dandy dressed in frilly and expensive clothing. Not known for his intellect, Sir Percy is liked, however, for his droll wit. The Comtesse's son offers to duel Sir Percy to rectify his mother's slight, but Marguerite defuses the scene by mocking the absurdity of the situation.
She later excuses herself so that she may say a tearful farewell to her brother, Armand, who is returning to France. Armand asks if she has told her husband the reason behind her apparent betrayal of the Comtesse's cousin, but she has not. Because of this, Sir Percy's love for her has cooled and their relationship is strained.
Back in the inn, Marguerite runs into Chauvelin, a French diplomat and spy, intent on finding the identity of the Scarlet Pimpernel. He tries to enlist Lady Blakeney in his pursuit, but she refuses. She has no idea who the mysterious man is and she has nothing but admiration for his brave deeds.
Sir Andrew and Lord Anthony talk together after they assume all the other guests at the inn have gone to bed. They need to be ready for the next phase of their leader's plan to rescue the Comtesse's husband, the Comte de Tourney. They allude to the fact that Marguerite's brother, Armand, is actually one of their band and will aide in the Comte's escape since no one yet suspects him of being in league with the Scarlet Pimpernel.
As they bend close to the fire so they can read a letter containing their next directives, they hear a noise. They are set upon by Chauvelin and his men, who knock them unconscious, steal their papers, and then carry them out of the inn. Chauvelin finds a note written by Marguerite's brother and realizes it is a way to blackmail her to help him find the Scarlet Pimpernel.
Several days later, Chauvelin approaches Lady Blakeney in her private box at the opera. He tells her about Armand's note and vows to have her brother arrested for treason if she doesn't help the French cause.
Heartbroken, Marguerite asks what she must do. Chauvelin explains that at Lord Grenville's ball, which she will attend following the opera, she must watch Sir Andrew Ffoulkes. Chauvelin knows that the Scarlet Pimpernel has set up a meeting with Sir Andrew for sometime during the ball. Marguerite must inform the French spy of Sir Andrew's actions and get him any information she can about the Scarlet Pimpernel. If she doesn't, her brother will go to the guillotine. Lady Blakeney reluctantly agrees.
Lord Percy arrives to take Marguerite to the ball. She desperately wishes to admit her turmoil to her husband, but his cool behavior forces her to shoulder her burden on her own. At Lord Grenville's ball she manages to catch Sir Andrew alone, reading a missive from the Scarlet Pimpernel. She pretends she thinks it is love letter from a rival and playfully steals it from him before he can burn the note. She glances at it for only a moment before handing it back so Sir Andrew will not suspect she's read any of it.
Later, she reluctantly informs Chauvelin that the Scarlet Pimpernel will wait in the supper room at 1:00, in case Sir Andrew has any questions for him. The note also inferred that the Scarlet Pimpernel would set off for France the following day. Chauvelin is thrilled with the information and promises to send Lady Blakeney her brother's incriminating note as soon as the Scarlet Pimpernel has been identified so that she may destroy it.
Marguerite wrestles with her betrayal throughout the evening, knowing it had to be done to save her brother, but wanting to warn the Scarlet Pimpernel of the trap being laid for him. Chauvelin arrives in the supper room before the appointed time so he can wait for his prey. The room is empty except for Lord Percy Blakeney, who sleeps on one of the couches.
Later, Marguerite sends a messenger to find her husband to tell him she'd like to start for home. When the messenger returns, she learns that Lord Percy was in the supper room asleep along with Chauvelin. Marguerite is convinced that Sir Andrew must have warned the Scarlet Pimpernel that there might be a trap and fears that Chauvelin will blame her and in turn execute her brother. When she speaks with Chauvelin, he tells her that no one else entered the room. As he knows that the Scarlet Pimpernel will leave for France in the morning, Chauvelin will also hire a boat to follow him there. If he succeeds in finding him, he will free Armand.
Lord and Lady Blakeney return home. Marguerite, desperate for help for her predicament, finally admits the truth to her husband about her betrayal of the Comtesse's cousin. She'd been tricked by members of the revolution into the betrayal and had done all she could to save the family. She never told Percy the entire truth because she'd hoped he would trust her and not believe the rumors spread by strangers. She begs her husband to help her brother, and although his love for her appears to have died, he promises to help Armand. Marguerite enters their home still conflicted. She is glad for Percy's help, but saddened by his coldness. Lord Blakeney remains on the steps outside and breaks down in tears. His love for Marguerite is obvious as he kisses the steps she walked up.
Marguerite spends the night in restless sleep, realizing that she truly loves her husband. She believes his aloof manner to be a mask he is wearing because she hurt his pride by hiding the truth of her betrayal. She is awakened when a letter is pushed under her door. It is from Percy and informs her that he has been called away on business. She runs outside to talk with him before he leaves. After much prodding, he admits his errand has to do with Armand.
Marguerite returns to the house after he leaves. She notices Lord Percy's study door is open. She has been forbidden to enter it, and she's never had an interest before; but now something draws her inside. She is surprised by its stark and organized appearance. She understands that her husband's mask extends not only to her, but to those around them. He is not the fool people think he is, but an astute business man. She notices something on the floor. Upon further examination, she discovers it is a signet ring imprinted with the symbol of a pimpernel flower.
Suddenly, all the pieces fit together, and Marguerite understands the full extent of her husband's disguise. He is not the foppish Lord Blakeney, but the elusive Scarlet Pimpernel. A messenger soon arrives from Chauvelin. He has sent Armand's letter to her, signaling to her that he knows Lord Blakeney's true identity as well. Marguerite is bereft. By saving her brother, she has condemned her husband to death. She enlists the aid of Sir Andrew, and together they set off for Calais to try and intercept Sir Percy before Chauvelin captures him.
Once on French soil, Lady Blakeney and Sir Andrew travel to a desolate inn. The innkeeper confirms that Lord Percy is a guest there and will be returning soon. Sir Andrew leaves Marguerite at the inn while he searches for Lord Percy in town. Marguerite hides in the inn's attic and waits for their return.
Chauvelin enters the inn disguised as a cleric. He orders his secretary to return with several soldiers so they can apprehend the Scarlet Pimpernel. He tells the man to assign other soldiers along the roads out of town. They must watch for a tall stranger. He can't describe him further as the man will be in disguise, but Lord Percy will not be able to hide his height. Marguerite listens to the exchange with despair. She believes her husband's capture is unavoidable and prays now only for the chance to tell him how much she truly loves him before he is taken away.
Soon after Chauvelin's man leaves, Lord Percy strides into the establishment. Chauvelin must keep his prey at the inn until his men arrive and so tries to act nonchalant with the Englishman. Lord Percy engages Chauvelin in conversation as he eats dinner while Marguerite watches in terrified silence from her hiding place. Lord Percy asks Chauvelin if he'd like a whiff of top-notch snuff he's just acquired. Too late, the Frenchman falls into a trap, as Percy has filled the snuffbox with pepper. Lord Percy leaves while Chauvelin is incapacitated with a sneezing fit.
Chauvelin's soldiers return with news about the Scarlet Pimpernel. He has been seen in town talking with a Jewish man about renting his horse. Chauvelin insists on talking to the man. The soldiers can't find him, but bring another Jew who claims to be his friend. This Jew explains that an Englishman borrowed his friend's lame horse to journey to a remote hut.
He offers Chauvelin the use of his horse and cart so he can catch the man. Chauvelin agrees, but insists the Jew come with him. If they find the Scarlet Pimpernel, the Jew will be rewarded. If they don't, he will be beaten, perhaps to death. Lady Blakeney secretly follows the soldiers as they take the Jew and his cart along a deserted road.
Chauvelin is upset when they don't overtake the Scarlet Pimpernel, but the Jew does guide them to the hut where the Englishman is to rendezvous with the prisoners he's helping to escape. Other soldiers have been to the hut and heard people inside it. Chauvelin orders them to keep watch but makes no moves until the tall Englishman arrives. He also orders the Jew to wait with his horse and cart until he and the soldiers return with their prisoners. The man promises to wait, but cannot promise not to scream if something should frighten him. Chauvelin reluctantly takes the man with him down the path to the hut.
Marguerite, tired and bleeding from the long walk, spots her husband's ship anchored near the shore. She runs toward the hut to warn her husband of the danger surrounding him, but is captured by Chauvelin. He orders her to keep quiet, but when she hears her husband's voice singing in the darkness, she screams and runs again toward the hut. She is knocked unconscious. When the soldiers enter the hut, they discover it is empty. Those standing guard tell Chauvelin that they let the men inside leave because he told them not to arrest anyone until the tall Englishman appeared. Canon fire from Lord Percy's boat signals their departure.
Chauvelin is furious until he remembers he heard Lord Percy singing, so the Scarlet Pimpernel must still be nearby. His soldiers find a note inside the hut setting up a new rendezvous point. Chauvelin and his soldiers leave to find him, but not before beating the Jew for his failure to get them to the hut in time.
Marguerite wakes to hear someone with a British accent cursing. She recognizes the voice as her husband's and searches for him in the dark. She comes upon the Jew, beaten and tied up along the path and realizes it is Percy. Sir Andrew, disguised as a French soldier, arrives to guide the couple to the ship. He's sent Chauvelin on a wild goose chase to find the Scarlet Pimpernel, so they have plenty of time to rendezvous with Armand and the other prisoners. Although Sir Percy has been severely beaten, he carries his beloved wife to the boat where they are carried safely back to England. The couple's love for each other has been renewed, and sometime later they help celebrate the wedding of Sir Andrew Ffoulkes and Suzanne.
