A commercial transport vessel on a routine mission is suddenly forced out of hyperspace into a black and starless void, where they discover an abandoned ship — the Slayton — which disappeared ten years ago.

Trapped in the void, the crew of the Nestor begin to see strange creatures inside their ship. After scanning the local space they find a huge chunk of dark matter and two spaceships: an alien craft and the derelict Slayton. After moving closer to the alien craft they begin to see more and more alien creatures appear on board their ship. Suspecting that the aliens may have attacked and killed the crew of the Slayton, they panic and begin shooting at them, to no effect. The pilot of the Nestor, Paul Stein, suddenly sees an apparition of his older brother Kevin (one of the crew of the ill-fated Slayton), who explains that they are all dead and disappears.

Commander Manning orders the Nestor moved away from the alien craft and towards the derelict Slayton. As they get closer, John Owens, captain of the Slayton appears. He explains that he cannot touch or feel them because he is no longer alive... he is some kind of ghost, trapped forever inside the pocket of space created by the dark matter. If they die here, as he and his crew did, their "essence" or "souls" will be trapped too.

After analyzing the records of the Slayton, they realize that the aliens did not attack. They were attempting to dock with the Slayton in order to escape. They make contact with the alien "ghosts" and use their plan. The dark matter is made up of high frequency superstring particles which are immensely heavy, add energy and the frequency lowers as does its mass therefore releasing the pocket in space that is holding everyone prisoner. The crew release the "ghosts" and escape themselves by turning the engines of the Nestor and the Slayton on the dark matter. Paul confronts Kevin's ghost over an old secret shame and gains confidence from the resolution to trust his own judgement.

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Wikipedia