Fifteen-year-old Patrick (Kevin Zegers) has spent many summer holidays with his parents at their cottage on a small island off the coast of South Carolina. In recent years, a major oil company developed on the island, polluting the local environment and damaging tourism. At the beginning of the film, a crate of large reptilian looking eggs is accidentally shipped to the island and discarded on the roadside by a driver. Twenty years later, the Connally family arrive at the island to return to their summer vacation home. Later during their stay, Patrick ventures out into the long-grass with his dog, Buster, and encounter a strange baby lizard. In an attempt to catch the lizard, Patrick stays out later than usual concerning Mr. and Mrs. Connally, who go out looking for him. Patrick decides to head home after hearing his parents calling out to him and is attacked by an unseen creature. Barely escaping, he is traumatized when he witnesses his parents, along with Buster, eaten alive by the still unseen creature(s). Patrick survives and is found in a state of shock.
In an undetermined amount of time later, Patrick's grandmother reaches out to Victoria Juno (Jill Hennessy), a young psychiatrist, to come and help Patrick come to terms with his grief and avoid sending him to a mental institution. His aunt Annie (Nina Landis), who is highly protective of Patrick is indifferent towards Victoria's presence and adamantly against him returning to the island. Victoria, with the grandmothers support, takes Patrick back to the island and are also accompanied by Annie. While still settling into the Connally's old vacation home, Annie is attacked and wounded. While Victoria tries to tend to Annie's wounds, Patrick is awakened by a growling and decides to come downstairs for a glass of water. While in the kitchen, Patrick has a flashback to the attack on his dog and runs to Victoria panicked. When she asks him what he saw, he points behind her to reveal a massive Komodo dragon. Annie is then killed by the creature and Victoria and Patrick barely escape with their lives—also revealing that there are several more dragons.
They later find the boat captain, Martin, severely injured. While driving frantically, they nearly crash into Oates (Billy Burke) and his sidekick Denby (Paul Gleeson), who were sent to kill all of the reptiles. Oates and Denby check on them and tend to Martin, who is beginning to succumb to an infection from his wounds—Oates explains it is an infection of several bacteria strains in the Komodo's saliva allowing them to track their prey. Oates and Denby call for help from Bracken (Simon Westaway), the man who sent them on the island to kill the Komodo dragons and is also helping Oates with legal problems.
Bracken refuses to take them off the island until they kill all of the dragons. Patrick suddenly runs off into the long-grass and separates from the group. Victoria tries to follow after him but is pulled back onto the road by Oates. Denby then says that Patrick cut out the heart of a Komodo dragon that had previously been killed. The group travel down the road to the oil company office station to seek shelter and get medicine for Martin. He later dies due to his wounds as well as Denby after he is attacked in another room. During this time Bracken radios Oates and says a helicopter will be coming by soon and that the dragons should be all killed by that time. Taking Denby's body to a higher section of the station, he is consoled by Victoria. Oates reveals that he was a former biologist and his wife a geologist hired by the oil company to survey the environment; while in the field, Oates and his wife separated and never sees her again afterwards. The local police thought Oates killed his wife and began to prosecute him—with no evidence to prove his innocence, Bracken presented Oates with an escape in return for taking care of the Komodo "problem." Victoria similarly confesses that she feels that she has failed in trying to help Patrick overcome his past.
They head off in search of Patrick at his old hang-out which turns out to be a filtration center. Separated, Victoria is attacked by one of the Komodo dragons but she is saved by Patrick. Victoria fails to persuade Patrick to come with her and he runs off again. She is then attacked by another Komodo dragon. Meanwhile, Oates is attacked by one of the creatures and manages to kill it however he is bitten. He then comes and saves Victoria from the attacking dragon by shooting it. They find Patrick again. Victoria then convinces him to come with them as she finally helps him overcome his grief—she tells him about how the oil company covered up the Komodo dragons inhabiting the island and that his parents death was not his fault. Immediately afterwards, one of the remaining Komodos attacks them. Oates manages to lure the dragon away into leaking oil/gasoline and attempts to kill it by igniting the oil with one of Denby's cigars. The dragon escapes the fire and rushes after Victoria, but she kills it by using a rock to bash in part of a broomstick handle into its head that she earlier injured it with.
The helicopter finally arrives along with Bracken. Oates turns up at the station alive and steals the helicopter to leave Bracken on the island with the creatures. Victoria and Patrick are trying to make their way back to Martin's boat when the last Komodo dragon tracks them down. It traps them by the coast, however, Oates suddenly flies over the hill in the helicopter and saves them by killing the Komodo dragon with a flare gun. They return to the mainland unharmed. While resting on the sidewalk back in town, the sheriff stops by to ask them if everything is all right. Patrick responds "Never better".Jill Hennessy as Victoria
Billy Burke as Oates
Kevin Zegers as Patrick Connelly
Michael Edward-Steven as Martin Gris
Paul Gleeson as Denby
Nina Landis as Annie
Simon Westaway as Bracken
Bruce Hughes as Mr. Connelly
Jane Conroy as Mrs. Connelly
Melissa Jaffer as Grandmother
Brian McDermott as Sheriff
Nique Needles as Hippie
Komodo had a limited theatrical release in summer 1999, with a VHS release in November of the same year. The DVD format of the film followed. The film was distributed by the Eastern limited branch of Scanbox Entertainment, Scanbox Asia Pacific Limited.