Set in 1973, a team of scientists decipher a mysterious signal from space and discover that it provides instructions to build a powerful super-computer. Once built, this computer provokes argument between two of leading team members, Fleming and Dawnay, over the machine's real intentions as it provides further instructions to create a living organism, which Dawnay starts to develop. Later it appears to compel lab assistant Christine to commit suicide, and when the organism is fully developed, it appears in the exact form of Christine, and named Andromeda. But what is the purpose of this "creature" ...?