In the not-too-distant future of 1970, a mysterious signal from space arrives with instructions to build a powerful super-computer. Once completed, the evice's motives provokes discourse between scientists John Fleming and Madeleine Dawnay as further instructions are to create a living organism, which Dawnay develops. The entity compels lab assistant Christine to commit suicide, and, upon manifestation, adopts her form, now known as Andromeda.

Esmond KnightProfessor Ernest Reinhart

Peter HallidayJohn Fleming

Patricia KnealeJudy Adamson

Noel JohnsonJ.M. Osborne

Julie ChristieChristine Jones / Andromeda

Donald StewartGeneral Vandenberg

Geoffrey LewisDoctor Geers

Mary MorrisProfessor Madeleine Dawnay

John HollisKaufman

Peter HenchieEgon

Frank WindsorDennis Bridger

John Murray ScottHarvey

Jack MayMajor Quadring

John NettletonHarries

Peter DucrowDoctor Hunter

Ernest HareMinister of Science Ratcliff

Brenda PetersSecretary