The novel “Alien Universe” by E.C. Tubb was published for the first time in 1952 under the pseudonym Volsted Gridban and reprinted in 2009 as “The Green Helix” under the author’s real name.

Caleb is the captain of his own cargo spacecraft, an old spaceship with which he manages to make some money despite the competition from big space corporations. He tries not to worry about the disappearance of various spaceships in hyperspace but the problem becomes important for him when Professor Armitage offers him the possibility of obtaining a huge profit if he finds his daughter, among the passengers of one of the missing spaceships.

Only one of the missing spaceships has been found but Professor Armitage claims that there are aliens at work attacking human spaceships. Caleb agrees to go on a journey to an entirely unknown destination that leads them into another universe.