From the ocean depth, terror stalked mankind – monsters gorge at the bottom of Luzon Deep, a vessel suddenly disappears in a mysterious curtain of foam and thousands of maddened fish writhe trapped in an ocean abyss. The superstitious fishermen of the Philippines put it down to ‘the things that listen’ – The Listeners. Radar expert Terry Holt and the crew of the Esperance have to devise a weapon against the huge, horrific squid-like creatures which threaten mankind’s existence.