
In the peaceful Appalachian hills of eastern Kentucky, toxins are being dumped into abandoned mines, causing environmental havoc, but the locals, mindful of their jobs and the power of the mine owners, can do nothing. EPA CID agent Jack Taggart is sent to investigate, after a fellow agent is found dead, probably not by accident. The EPA has received an anonymous letter from Jackson, Kentucky, and Taggart goes there undercover to continue his colleague's investigations.

It is discovered that Hanner Coal Company, owned by Orin Hanner Sr., is being paid to dump toxic waste into an abandoned coal mine shaft, so Jack is assigned to go to the small town of Jackson, where his cover is that of assistant and volunteer carpenter to a local church. He stays in a room in the church's basement, and begins his cover work by repairing the roof at a house where one of the children is sick because of the pollution. He attempts to question the family, but they do not have much to say. He has little better results elsewhere; even the man who tipped off the EPA is decidedly taciturn. While testing the water, Taggart wanders into a local marijuana field, and is accosted by the growers. After disarming them, he tells them that he has no interest in arresting them.

The men responsible for the other agent's death soon notice Taggart's presence. As a newcomer to the small local community, he is threatened by Hanner's son Orin, Jr. (Brad Hunt), the incompetent local tool of the company, the corrupt local Sheriff Lloyd Foley, and several thugs that work for them. The thugs in question start by leaving two rattlesnakes in his dwelling; Taggart responds by capturing the snakes alive and leaving them in the pickup that the thugs were driving, causing them to crash. Soon after, five of them attack him while he is buying supplies, and receive a severe beating as a result. Orin then orders one of his truck drivers to arrange an "accident" by running him off the road, but Taggart escapes alive while the driver is killed.

While these conflicts are occurring, Taggart strikes up a relationship with Sarah Kellogg, a young woman who lives in the town. She is regarded as an outcast because of her father's murder, a crime of which she was accused but not convicted. Eventually, she agrees to testify against Orin and his people, much to the anger of her brother Earl, who actually committed the crime, after their father found out about his sexual abuse against her. He sets the church on fire, killing the preacher who was helping Taggart in the process, and then attempts to collapse the mine with Taggart inside it. Taggart escapes, but several mercenaries are killed, including Earl.

With evidence and a witness, Taggart calls the FBI to take Sarah into protective custody. However, they are revealed to be corrupt, and a firefight ensues. Taggart kills one agent, then sends the second back to Orin with a message that he'll be coming for him next. However, when Orin is arrested and charged, he gets off with a slap on the wrist for the environmental violations. Taggart goes back into the town and fights his way past the last of Orin, Jr's thugs, then demands the truth from him. Orin agrees to turn state's evidence, implicating his father on racketeering, conspiracy, and murder charges. Taggart goes to a casino to arrest Orin, Sr. Upon hearing about the reception awaiting him in federal prison, Orin produces a gun and resists, but Taggart shoots him in the shoulder and he is taken into custody. Taggart then returns to Jackson, where he is reunited with Sarah.
Steven Seagal as Jack TaggartMarg Helgenberger as Sarah KelloggHarry Dean Stanton as Cotton HarryStephen Lang as Earl KelloggBrad Hunt as Orin Hanner, Jr.Levon Helm as Reverend Bob GoodallKris Kristofferson as Orin Hanner, Sr.Mark Collie as HatchAlex Harvey as SimsEd Bruce as Sheriff Lloyd FoleyAmelia Neighbors as Edie CarrRichard Masur as Phil PrattRandy Travis as Ken AdamsMarty Stuart as himselfTravis Tritt as himselfErnie Lively as ToddJames Mathers as Marshall Adams
The film was shot on location in and around Kentucky; parts of the "truck chase scene" were shot at Natural Bridge State Resort Park. Some of the opening scenes were filmed at Cumberland Falls State Resort Park. The cave scenes were filmed in the Great Saltpetre Cave.

Fire Down Below was released on September 5, 1997. It grossed $6 million on its opening weekend and took in a total US gross of $16.2 million.

The film has an 11% approval rating on Rotten Tomatoes based on 27 reviews; the average rating is 3.3/10.
The film was nominated for four Razzie Awards:
Worst Picture – Julius R. Nasso (lost to The Postman)Worst Actor – Steven Seagal (lost to Kevin Costner for The Postman)Worst Screen Couple – Seagal and his guitar (lost to Jean-Claude Van Damme and Dennis Rodman for Double Team)Worst Original Song – "Fire Down Below" (lost to The Entire Song Score of The Postman)