The same characters that survived the Forever War, Marygay and William, are now faced with a very different problem in this book. All the surviving veterans of the Forever War were given the choice to go and live away from Earth, away from Man.

Man is the result of what had been the human species, but is now made up of cloned individuals, all identical, which tap into what the they "The Tree". The Tree is a vast collective experience, enabling them to think together and form consensus.

The veterans live on a world known as MF, with a long orbit that leaves the planet cold for most of the year. Man said that they wanted humans to breed so that if anything went wrong with cloning, the would have more genetic stock. But they don't leave the planet alone, and William feels more and more that they are simply lab rats, with no real freedom.

William and the older vets hatch a plan to escape. They will take back the old ship known as the Time Warp, which Marygay used to wait for William at the end of the War. They will travel up, above the galaxy, and back, and acceleration will mean that they age ten years, while MF goes through forty thousand.

Their plan is discovered by Man, who taps into the Tree on MF to make a decision about it. They decide to help, and to allow one hundred and fifty people to leave on the ship. They only need to wait ten months for approval from the Earth Tree.

Preparations begin and they are almost ready to leave when word comes back from Earth, they have been denied permission. William and the other vets refuse to accept this, and go back to their original plan to steal the ship.

They manage to get into orbit, using a Man as a hostage, and find one of the alien Taurans aboard. The Man and the Tauran explain that it had been predicted that they would attempt something of the type. William and Marygay threaten to crash the ship, causing damage that will make the planet unlivable for years.

Man and the Taurans on planet agree to let them leave, and explain that the Man they have and the Tauran on board are going with them. The Tree on Earth does not know the humans the way that the Tree on MF does, and they are more willing to help.

Everyone is loaded aboard and they set off. But things quickly start to go wrong. Everyone is suffering from depression, and weird unexplained events occur. One of the food storage areas becomes a vacuum without cause, a floor surface becomes tacky for no reason, and things break or fail. Finally the antimatter which powers the ship vanishes.

They pile into emergency lifeboats and head back to MF. When they arrive, they find everyone gone. Clothes lie in piles as though the people simply evaporated out of them, houses and vehicles are left empty. There is no explanation, and the vets focus mainly on preparing for the coming winter so that they can survive.

When winter hits, and there is less to do, they decide to mount an expedition to earth. When they arrive it is exactly the same as on MF. But they do encounter one strange creature, which calls itself an Omni. It claims that it's species, which can change shape, has lived on Earth since long before humans, and that they helped both humans and Taurans develop culture.

The humans are all sceptical, and when of them suddenly explodes, they wonder if the Omni is responsible. More Omni arrive, and more people die, and they speculate about why it has all happened.

A creature reassembles on the dead humans and explains that it has been using the galaxy as an experiment. That all the fundamentals of science and physics that they believed were constant were actually controls created for the experiment. When they tried to fly above the galaxy, it was like rats escaping from their cage.

It says that there are others of itself out there, but doesn't know if there is a higher being than itself. It leaves, saying that now they are on their own. When it goes, suddenly there are thousands of naked people, all the ones who had disappeared.

Marygay and WIlliam return home to MF, and find that they are happy to return to their old life, in their old town.