Monstroid is a 1980 American film directed by Kenneth Hartford. It was originally titled Monster when the film was first announced in 1975 and again in 1977, and suffered numerous cast changes (most notably Keenan Wynn who was still billed on some early video releases). The film was eventually released in 1980 as Monstroid, and is also known as Monstroid: It Came from the Lake (American DVD box title) and The Toxic Horror (American alternative title). A novelization written by Peter Crowcroft was released concurrently with the film.
The film bills itself as being based on a true story that took place in "Chimayo, Colombia" in 1971. However, the village is entirely fictional, and the film was actually shot in Chimayo, New Mexico and Ambalema, Colombia.
One night in the fishing village of Chimayo, Colombia, María Reyes witnesses a monster devouring her husband José. Some years later, the American cement manufacturer Durado Cement dispatches troubleshooter Bill Travis (James Mitchum) to Chimayo to restore order to their manufacturing plant there: an anti-corporate activist named Victor Sanchez has been exploiting the villagers' fear of the monster to stir up hostility against Durado, which has been polluting their fishing waters in Lake Chimayo. In the process, María has become ostracized from the villagers: a group led by a man named Carlos calls her "la bruja" ("the witch"). In addition, Travis must silence an American TV reporter named Patty Clark who has been exposing the pollution of the lake.
In Chimayo, children Andrea and Glen Anderson observe strange ripples in the lake. Glen claims they belong to an animal he has been sighting in the lake for some time. Their father Pete (Anthony Eisley), administrator of the Durado plant, is introduced to Mayor Montero and his daughter, helicopter pilot Juanita. Sanchez meets up with Carlos in a church, and together they plot to drive out the Americans and the monster he thinks was created by the pollution of the lake. When María goes to visit José's grave, Carlos's men attack her.
Juanita picks up Travis at the airport. When he gets to Chimayo, he is accosted by Clark, and curtly refuses any interviews. Meanwhile, Pete is trying to break up with his secretary Laura to pursue a new affair with Juanita, but can't bring himself to do it. He visits her again that night when she is skinny dipping in the lake, and successfully breaks up, but the monster emerges from the lake and kills Laura after he leaves. The town is busy celebrating its 200th anniversary and the body goes undiscovered until the next morning.
Travis and the plant doctor investigate the killing and link it to José's death. Glen tells Travis about the animal he saw, convincing Travis that there is something in the lake. Soon afterwards, Sanchez meets Travis and threatens violence against Durado. Travis and Montero confront Clark about her reporting, and they negotiate exclusive rights to the pollution story in exchange for her temporary silence. Travis also calls his boss Barnes (Philip Carey) to request sonar equipment with which to track the monster. Determined to prove the monster's existence, Glen decides to stake out the lake at night. He drags Andrea along, and they manage to take some photos of the monster before it attacks some drunken fishermen.
They present their evidence to Travis while the village continues celebrating their anniversary. Simultaneously, Sanchez sets some plastic explosives to blow up the plant. However, he gets trapped after lighting the fuse. Meanwhile, a party of men chases María, whom they blame for all their troubles. The town priest (John Carradine) claims that he can exorcise her, but the men are unconvinced and burn her at the stake. Sanchez's bomb goes off, and the next day Travis reveals that the plant has been badly damaged and María severely burned. Consequently, she is airlifted to a Panamanian hospital in Chimayo's only helicopter to get treatment.
Travis comes up with a plan to kill the beast: he stuffs some explosives into a goat carcass, which he will hang by the detonator cord from a helicopter. In order to obtain a new chopper, Juanita lures some rescue workers with a fake mayday and hijacks their craft at gunpoint. They get to the lake and the Nessie-like monster takes the bait, but Travis loses the detonator and dives in after it. A local policeman distracts the monster by circling it with his boat, and thus buys Travis enough time to retrieve the detonator and blow the creature to pieces.
However, some time later the Andersons are down by the lake again, and their German Shepherd finds a large egg. A reptilian creature hatches out of it, and the film ends as the camera pans over a clutch of dozens of similar eggs.James Mitchum as Travis
John Carradine as The Priest
Philip Carey as Barnes
Anthony Eisley as Pete
Andrea Hartford as Andrea
Glen Hartford as Glen
Coral Kassel as Laura
Aldo Sambrell as Carlos