Violinist Niccolo Paganini lives in poverty in Genoa, but sees a way out of his situation when he hears that the composer Pasini is holding a competition - with an expensive Stradivarius violin going to the musician who can most convincingly sight-read his difficult scores.

Paganini's talent is such that he believes the Stradivarius is his by right - but he can't afford to travel to Pasini's home of Parma. A solution is at hand in the form of French aristocrat Jeanne de Vermond, who agrees to fund him in exchange for Paganini helping to spring her father from prison.

On the way to Parma, Paganini meets Germi, an unsuccessful lawyer, who agrees to become his manager. In Parma, Paganini enters Pasini's competition and wins. A delighted Jeanne invites him to play for her friends, but he is angered by their ignorant and philistine reaction, quarrels with Jeanne, and abandons her in favour of childhood sweetheart Bianchi, who has followed him to Parma.

Paganini takes to gambling and loses all his money. He is forced to pawn his hard-won Stradivarius, but gambles away those proceeds as well. This causes complications as Germi has arranged a public concert, but Jeanne comes to the rescue by paying off the pawnbroker. The concert is a huge success, and Paganini and Jeanne fall in love.

However, external events take a turn in the form of Napoleon's army invading Italy, under Paul de la Rochelle, an officer whom Jeanne's parents are keen for her to marry to cement their social and political standing - an alliance backed by Napoleon as well. Bianchi pours fuel on the fire by telling Jeanne's mother that she is having an affair with Paganini.

Jeanne tells Paganini that her parents want her to go to Paris to marry Paul. He agrees to elope with her, but Napoleon threatens Paganini if this goes ahead. Instead, he absorbs himself in his work, quickly becoming the most successful violinist in the country, with Bianchi at his side.

Paganini meets Jeanne again while on tour in Paris. Hearing of this, Paul challenges him to a duel. Both Jeanne and Bianchi are horrified by this and set aside their differences to try to persuade him to reconsider - but they are too late: Paganini has been wounded in the arm.

Although the wound heals, Paganini loses all interest in his music. Jeanne uses her contacts to arrange an audience with the Pope, which lifts him out of his torpor. The Vatican concert is his most successful yet, he is decorated by the Pope, Paul agrees to break off his engagement to Jeanne, and she and Paganini are united for good.