The film stars Van Damme as a paratrooper legionnaire; when his brother is seriously injured he returns to Los Angeles to enter the underground fighting circuit to raise money for his brother's family.
The film's cast and crew included two people who had appeared in an earlier Van Damme film: Michel Qissi (a good friend of his) and Sheldon Lettich. This was the second time Qissi played a villain in a Van Damme film, the first being notably as Tong Po in Kickboxer (1989). Lettich helped write one of Van Damme's breakthrough films, Bloodsport, along with another Van Damme film, Double Impact.
Lyon Gaultier is a paratrooper in the French Foreign Legion, stationed in Djibouti, North Africa. His brother, who is married to an American woman in Los Angeles, is burned alive during a drug deal gone wrong and suffers third-degree burns, dying shortly afterward. Lyon deserts his legion when he finds out they have been withholding letters from his brother's wife and ultimately refuse to let him see his dying brother. He steals a jeep and escapes through the desert, finding work on a tramp steamer headed for the U.S. Meanwhile, the Legion commanding officer also travels to the States, arriving at the French Embassy, where he is told that Lyon's desertion is ranked at low importance with the LAPD, so he orders two of his own Legionnaires to do the job.
Lyon arrives in New York City and travels to California to be with his brother's family. Along the way, he meets Joshua, a man who runs fights for money, and also learns that he cannot avenge his brother's murder, as he failed to identify his killers before dying. Tagging along with Joshua, Lyon meets Cynthia, who organizes underground fights for the rich elite and decides to sponsor him. Figuring that this would be the best way to earn the money his family needs, Lyon fights in no-holds-barred bare-knuckle fights to finance the trip. Once they reach L.A., he tracks down his brother's widow, who is reluctant to accept financial aid, even though she obviously needs it, because she is angry with Lyon for "deserting" his brother years ago. This is when he finds out that his brother has already died. Joshua introduces Lyon in the fighting circuit as the titular "Lionheart," derived from "Lyon." Lyon continues fighting, and Joshua uses the prize money to give to Lyon's sister-in-law in the form of checks, with Joshua claiming to be from a life insurance firm her husband allegedly subscribed to long ago.
Meanwhile, the two Legionnaires catch up with Lyon in Los Angeles. Lyon fights them off, but suffers a broken rib. Cynthia decides to take advantage of Lyon's string of victories by stacking the odds in favor of a massive, brutal fighter named "Attila the Hun", who has so far been unbeatable. Cynthia stacks the odds by smuggling a video of Atilla fighting poorly from one of his earlier bouts, which as expected fails to impress the odds-makers. Cynthia later reveals Attila's true prowess to the Legionnaires, and she promises to deliver Lyon to them after he has been thoroughly humiliated and beaten. The Legionnaires agree to this, provided they can be in the audience.
Lyon's fight with Atilla is hampered by his broken rib. Atilla's trademark (deliberately withheld from Lyon) is to let his opponent tire themselves out before viciously breaking them, often killing them in the process. When it appears "Attila" has won, Joshua begs Lyon to give up, revealing that they were both used by Cynthia. Joshua, for the best of reasons (Lionheart's family), placed all of his own money on Attila as a form of "insurance," as all the odds are against Lyon winning. Lyon, angered by this news, bounces back and summons up all his remaining strength to defeat Atilla, subduing but not killing him. While bookies sideline Cynthia demanding she pay up, the Legionnaires capture Lyon. They escort him back to the apartment, where they give him some time to say his goodbyes before being returned back to Africa, where he will be court-martialed for desertion. Lyon tells his niece that he must go but to try to look for times when life can be good, which is emotional as she does not understand. However, just down the road, moved by the family's heartbreak, the Legionnaires decide to let Lyon go. They believe he has shown the Legion's values of honor, determination and service to others, both during the fight and helping out the family, and wish him luck in his new life in America. Ultimately, Lyon is shown running back to a pleased Joshua and joyous family.Jean-Claude Van Damme as Lyon Gaultier
Harrison Page as Joshua Eldridge
Deborah Rennard as Cynthia
Lisa Pelikan as Hélène Gaultier
Ashley Johnson as Nicole Gaultier
Brian Thompson as Russell
Voyo Goric as Sgt. Hartog
Michel Qissi as Moustafa
Tony Halme as security guard
Abdel Qissi as Attila
Director Sheldon Lettich had co written Bloodsport the film that turned Van Damme into a star. They had become friends and Van Damme was impressed with a short film Lettich made, Firebase, and agreed for Lettich to direct. The director later recalled
Lionheart was a defining film for Van Damme because I did not shy away from giving him considerable amounts of dialogue and character development throughout the film. I trusted him to pull this off, whereas before nobody else believed he could do much more than just deliver some fancy kicks and simple one-liners. Lionheart was the first movie to demonstrate that Van Damme was more than just a flash-in-the-pan "Karate Guy" who would never rise above simplistic low-budget karate movies.
In the film, Van Damme shows his backside in one sceen. While we were filming the scene in Lionheart where he takes a shower in Cynthia's apartment, he asked me if he might casually "drop his towel" and show off his butt for a brief moment. My reply was "Sure, if you're willing, why not? We can always use a different take later if we decide it's not a good idea." So we did one take where he casually lets the towel drop away, and then we later decided to go ahead and put that shot in the movie. Well, that became a very memorable moment for the ladies in the audience, and for the gay guys as well. Showing off his butt (clothed or unclothed) almost became a signature trademark of his after that.
The critical reception for the film was mixed, but was responded to negatively by most critics. On the film aggregate website Rotten Tomatoes, it holds an approval rating of 33% based on 12 reviews.
Lionheart performed well at the box office, debuting in 3rd position in the US with sales of about $7 million. The film dropped to 7th in its second week, and to 9th in its third. The film earned $24,078,196 worldwide on a budget of $6 million.
Director Sheldon Lettich says the film became very popular among his fans:
People love the characters. They're particularly fond of Lyon's motor-mouthed, self-appointed "manager," Joshua. Van Damme's female fans seem especially enamored of this film because it was the first (and possibly the best) to showcase JCVD's softer, more compassionate side. In Lionheart he's not fighting for revenge or to "honor his Sensei," or any of the usual motivations that are typical for these sorts of movies; he's fighting for his family. He's getting himself bruised and bloodied in these brutal street fights so that his little niece can get a new bicycle.