Starslave (Linford Mystery Library)

On several settled worlds of the Earth Confederation, towns had been destroyed by attacking alien vessels. Captain Kurt Varl was the only man to have fought an alien ship and destroyed it - the only survivor from a crew of thirty. He must lead another ship and crew into battle, knowing that as well as the alien raiders, he faced the things that lurked in limbo, existing in four dimensions and capable of transforming humans into things of screaming horror...