Helena, the orphan daughter of a famous physician, is the ward of the Countess of Rousillon, and hopelessly in love with her son, Count Bertram, who has been sent to the court of the King of France. Despite her beauty and worth, Helena has no hope of attracting Bertram, since she is of low birth and he is a nobleman. However, when word comes that the King is ill, she goes to Paris and, using her father's arts, cures the illness. In return, she is given the hand of any man in the realm; she chooses Bertram. Her new husband is appalled at the match, however, and shortly after their marriage flees France, accompanied only by a scoundrel named Parolles, to fight in the army of the Duke of Florence.
Helena is sent home to the Countess, and receives a letter from Bertram informing her that he will never be her true spouse unless she can get his family ring from his finger, and become pregnant with his child--neither of which, he declares, will ever come to pass. The Countess, who loves Helena and approves of the match, tries to comfort her, but the distraught young woman departs Rousillon, planning to make a religious pilgrimage.
Meanwhile, in Florence, Bertram has become a general in the Duke's army. Helena comes to the city, and discovers that her husband is trying to seduce the virginal daughter of a kindly Widow. With the connivance of the daughter, named Diana, she contrives to trick Bertram: he gives Diana his ring as a token of his love, and when he comes to her room at night, Helena is in the bed, and they make love without him realizing that it is her. At the same time, two lords in the army expose Parolles as a coward and a villain, and he falls out of Bertram's favor. Meanwhile, false messengers have come to the camp bearing word that Helena is dead, and with the war drawing to a close, Bertram decides to return to France. Unknown to him, Helena follows, accompanied by Diana and the Widow.
In Rousillon, everyone is mourning Helena as dead. The King is visiting, and consents to Bertram marrying the daughter of an old, faithful lord, named Lafew. However, he notices a ring on Bertram's finger that formerly belonged to Helena--it was a gift from the King after she saved his life. (Helena gave the ring to Diana in Florence, and she in turn gave it to her would-be lover.) Bertram is at a loss to explain where it came from, but just then Diana and her mother appear to explain matters--followed by Helena, who informs her husband that both his conditions have been fulfilled. Chastened, Bertram consents to be a good husband to her, and there is general rejoicing.