Leonard Whitting stars as Dr Victor Frankenstein, although in this version of the tale it is Henry Clerval (David)
McCallum) who is initally determined to play God by creating life in a laboratory. Clerval has discovered how to
preserve body parts and restore them to life, including an amputated limb. Clerval wants to use solar power to
create the "Second Adam", a new race of humans who would be physically perfect. Frankenstein agrees to
work with Clerval to create the new race, and they soon take advantage of a mine accident to obtain the body
parts needed for their experiment. They assemble their Adam (Michael Sarrazin) from the best bits of the dead
miners, and are poised to bring him to life. However, Clerval discovers that the severed arm, which can move
around on its own, has become diseased and withered, and Clerval realises that the process is reversing itself.
The shock of failure kills him, but Frankenstein misinterprets his dying words and proceeds with bringing Adam
to life, giving the creature Clerval's own brain.

The process works and the new Adam is a handsome, intelligent man who is soon welcomes into elite London
society, being passed off as a foreign relative of Victor who does not speak English. However, the process soon
begins to reverse and Adam starts to become the familiar disfigured Creature of Frankenstein lore. Victor rejects
his creation and sets about creating a perfect Eve, after being blackmailed by Dr John Polidori (James Mason), 
who discovers what Frankenstein has been up to. Things naturally end badly; Frankenstein and his new wife flee
to America, but the Creatures stows away on the ship. The crew (led by Tom Baker as the Captain in a brief role)
abandon ship. This leads to a final showdown between Frankenstein and his creation on an iceberg.