Tau Zero has been considered by some to be the ultimate science-fiction novel because its scope reaches to the end of the universe. After some exploratory missions to other stars, Earth decides to send a ship to Beta Three to establish the first extra-solar colony. Because of the vast distance involved, the ship travels at near-light speed, using a Bussard ramscoop to gather hydrogen particles as fuel. As the ship continues to accelerate, relative time slows down for those inside, so that years pass while the crew experiences mere days.
The Leonora Christine is crewed by fifty colonists who have volunteered for this mission knowing that they will never return to Earth. They represent the best and brightest of Earth’s scientists and engineers, as well as professional spacemen and-women who run the ship. Among them is Carl Reymont, the ship’s constable, whose military past qualifies him for the responsibility of maintaining order and authority. Reymont soon forms a relationship with the first officer, Ingrid Lindgren. The voyage goes well at first despite minor personnel problems that result from the boredom and isolation of spaceflight.
The voyage is jeopardized when the ship hits a patch of interstellar dust, damaging the braking system. The Leonora Christine is unable to slow down, and as its acceleration continues, more and more time passes because of the relativistic effects of the ship’s speed. The crew members experience psychological trauma as they realize that they may be trapped in the ship forever. Reymont uses his training in crisis and survival situations to instill renewed spirit and the will to survive. They purposefully accelerate even more, so that they can leave the galaxy and attempt to repair the damaged system in the less dense regions of intergalactic space. Their speed becomes so great that billions of years pass and the universe begins to contract. Most of the colonists are ready to give up at that point, but Reymont leads them in a bold plan to circle the shrinking universe until a monobloc forms, from which the cycle will begin anew. It is in this new universe that the crew repairs the braking system and locates a suitable planet for colonization. Reymont is at last able to lay down the heavy burden of leadership.