It was directed by Kevin Connor and starred Doug McClure, Peter Cushing and Caroline Munro. It was filmed in Technicolor, and based on the fantasy novel At the Earth's Core, by Edgar Rice Burroughs, the first book of his Pellucidar series, in token of which the film is also known as Edgar Rice Burroughs' At the Earth's Core. The original music score was composed by Mike Vickers.
At the earths core 1976 sci fi adventure
Dr. Abner Perry (Peter Cushing), a British Victorian scientist, and his US financier David Innes (Doug McClure) make a test run of their Iron Mole drilling machine in a Welsh mountain, but end up in a strange underground labyrinth ruled by a species of giant telepathic flying reptiles, the Mahars, and full of prehistoric monsters and cavemen.
They are captured by the Mahars, who keep primitive humans as their slaves through mind control. David falls for the beautiful slave girl Princess Dia (Caroline Munro) but when she is chosen as a sacrificial victim in the Mahar city, David and Perry must rally the surviving human slaves to rebel and not only save her but also win their freedom.
The film was made following the success of The Land That Time Forgot.
The movie was popular, becoming the 18th most profitable British film of 1976.
The film was featured in the season finale of the revived Mystery Science Theater 3000, the show's eleventh season overall, released on April 14, 2017 through Netflix.