A for Andromeda

From two hundred light years across the universe comes a message of terror... A new radio telescope picks up a complex series of signals from the Andromeda constellation - signals which prove to be a programme for a giant computer. When the computer begins to relay the information it receives from Andromeda, the project assumes a vital importance, for scientists find themselves possessing knowledge previously unknown to man - knowledge of such a nature that the security of human life itself is threatened.