Having seen Henri Helman's miniserie Lagardère, I am familiar with the story of Le bossu. I think the French are very good in creating swashbuckling stories: The Three Musketeers, Man in The Iron Mask, The Black Tulip, Fanfan la tulipe, Le capitan, Cyrano de Bergerac - to mention some of them. [If only Zorro was also created by a Frenchman!] Le bossu (=the hunchback) is one of the most enjoyable swashbuckling stories ever. Apart from the story, I wanted to watch this because of Daniel Auteuil and Philippe Sarde's music.
Gonzague (Fabrice Luchini) should inherit Duc de Nevers (Vincent Perez)'s fortune after his death, but his world tumbles down when he learns the Duc has a child from Blanche de Caylus (Claire Nebout), the beautiful woman whom he also loves very much. Gonzague hires Peyrolles (Yann Collette) and his men to kill the Duc, who is helped by his close friend Lagardère (Daniel Auteuil), whom he has taught his secret sword thrust. Gonzague succeeds in killing the Duc, but Lagardère marks Gonzague's right hand with his sword and swears that he will avenge the Duc of Nevers. "Si tu ne viens pas à Lagardère, Lagardère ira à toi!" (If you don't come to Lagardère, Lagardère will come to you!) Gonzague spreads the words that Lagardère is the killer of the Duc and his baby daughter. Meanwhile, Lagardère travels with a group of comedians, raising the child Aurore. Time passes and Aurore (Marie Gillain) accidentally kills a famous swordsman, using the secret sword thrust her 'father' has taught her. Gonzague realizes that Aurore is still alive. Lagardère, in order to meet Blanche and tell her that her daughter is still alive, disguises as a hunchback and gains Gonzague's trust. When the Duke of Orléans (Philippe Noiret) is about to sign the contract that will make Gonzague's dream come true: to own Mississippi, the hunchback presents Aurore as the true heir of Nevers and points at Gonzague as the killer.
The plots in Le bossu (released in the US as On Guard) and the miniseries Lagardère are not always the same. The ending, for example: in Le bossu, Lagardère ends up marrying Aurore, while in Lagardère he marries her mother. I must say that I enjoy the bits in the miniseries when Lagardère travels all over Europe to find and kill one by one the members of the gang who attacked Nevers in the fatal night and check whether any of them has a mark on his hand. I also like the title Lagardère better because the hunchback only appears in less than 1/4 of the movie, I think - even though it's the original title. (It's based on a book called Le bossu by Paul Féval.) However, Le bossu is still a much better title than On Guard.