At the beginning of the 20th century, British archaeologist Professor Aitken and his son, Charles, have hired Captain Daniels and his ship, the Texas Rose, to take them to sea.
The pair plan to use a diving bell designed by engineer Greg Collinson to search for proof of the lost city of Atlantis.
Grogan cuts the line to the diving bell, trapping Greg and Charles at the bottom of the sea, and another of the mutineers shoots the Professor in the back.
Atmir promises to take them to safety, telling them en route that Atlantis has seven different cities, the first two of which have been sent down to the ocean, while a third one is now deserted and empty.
Atmir takes the surface-dwellers through a prehistoric swamp inhabited by a millipede-like monster called the Mogdaan, before reaching the city of Vaar.
Greg and the Texas Rose crew make friends with Briggs, the captain of the long missing Mary Celeste.
Holding Fenn and Grogan at gun point, Sandy tells Greg, Charles and Daniels about the mutiny and the shooting.
Daniels convinces Sandy to hand over the pistols, but then turns the tables, revealing that it was he who shot the Professor, who had refused his offer to make a profit out of their discovery.
Kevin Connor called the script for Warlords "more intelligent" than others he had made with McClure "“because that’s what I’m trying to do with this film, put more comment and content into it... to make the audience aware of the folly of mankind in its broadest sense.
The film is set at the time of the Industrial Revolution because I wanted to show what the scientific discoveries would eventually lead us to in terms of war and technology.
"[9] According to academic James Chapman, the film opened at the box office strongly but "fell out of the top ten after only one week, a more rapid decline than its predecessors that can probably be attributed to stiff competition during the summer of 1978, including Revenge of the Pink Panther, Close Encounters of the Third Kind and Grease.
The clichéd characters are played in workmanlike fashion by all hands";[15] Sight and Sound wrote "the presence of Cyd Charisse, as a puppet-like but still comely Martian, provides some of the few moments of incidental pleasure in this dinosaur fantasy, routinely cobbled together.
"[16] Time Out wrote "As always, Connor's approach is commendably stolid, but this production lacks almost all the more pleasing elements of the earlier movies, and is sickeningly vulgar in its portrayal of Atlantis, right down to the leering emphasis on Cyd Charisse's legs";[17] TV Guide wrote "It's silly but harmless and won't offend anyone under 12 years of age";[18] and The Spinning Image noted the film was "scripted by former Doctor Who writer Brian Hayles, and has a similar strain of British idiosyncrasy about it, despite being an American co-production.
Rest assured, the rubber monsters familiar from the first three films are present and correct, as is the piling on of incident and special effects, regardless of how convincing they are on screen...it's a fairly enjoyable ride with generally witty performances and plentiful action.
"[19] Academic James Chapman felt Warlords was the "most interesting" of the 1970s lost world films "perhaps because it was an original screenplay rather than an adaptation of pulp literature.
The script has some pretension to seriousness in so far as it suggests an alternative history of the Earth in which the course of technological development has been determined by the survivors of the lost civilisation of Atlantis.