E.C. Tubb 
Green Helix 

Over a dozen spaceships had disappeared into hyperspace, never to return. The lost vessels included the Jason, the Starbird, and the Invincible. Everyone assumed that they had fallen victim to some mechanical failure. But the mystery deepened when the Invincible was found drifting in space, six months after vanishing. The ship’s engines were undamaged, the hull intact — but there was no trace of any living thing aboard; living or dead. No trace of its crew or the two hundred passengers. The ship was deserted! Something had happened to the ship, to the passengers and crew. Something in hyperspace — or somebody!