At night, uncharted depths from the North Sea they have lurked, growing in strength, growing in proportions, and striking terror in to the hearts of mariners down the untold centuries. Getting near a North Sea gas refinery from the east coastline of England, the TARDIS staff are instantly accused of sabotage. Many rig crews have mysteriously vanished, strange pressure build-ups have already been recognized, and in the refinery’s pipelines the physician can hear the constant, rhythmic beat of – what? Quickly the Doctor, Jamie and Victoria will see themselves at the unrelenting mercy from the deadliest & most terrifying foe they possess ever experienced… David Troughton reads Victor Pemberton’s comprehensive and unabridged novelisation, first published by Target Books in 1986.