But visitors Gerald Sternbruck and Ernst Carlsberg soon realise that the still waters of the lake conceal a frightful evil that preys on flora, fauna - and human beings.Then they discover that the same evil first manifested itself before the valley was flooded - and may have been the basis for H.P. Lovecraft's classic story The Colour out of Space.For fifty years one waman has been planning her revenge on the monstrous force which caused the strange shimmering colours -- and sucks the very life from the people in its clutches....

    Now the final nightmare must explode. Now the killing frenzy must begin...