Dead Space is set about 500 years in the future; 2508 to be exact. The protagonist, engineer Isaac Clarke, is aboard the USG Kellion when a mining ship (or "planetcracker") called the USG Ishimura sends out a distress signal. The crew of the Kellion boards the Ishimura to investigate, and are attacked by monstrous beings later referred to as Necromorphs. Isaac, Commander Zach Hammond, and Computer Specialist Kendra Daniels are the only members of the Kellion to survive the initial onslaught and they must work to repair the Ishimura's failing systems in order to stay alive long enough for someone to rescue them.
br>
Throughout the course of making repairs, Isaac Clarke learns that the deceased crew of the Ishimura had discovered the Red Marker while mining Aegis VII. The Red Marker is an important artifact of a religion called Unitology, and therefore once it was discovered, the Unitologist captain of the ship, Mathius, ordered the immediate retrieval of the Marker. Unfortunately for the crew, contact with the Marker resulted in delusions, hallucinations and the spreading of a virus that turned corpses into the mutated Necromorphs. Isaac also encounters his girlfriend, Nicole, at one point since she is a doctor aboard the Ishimura, but they can't meet face to face.
br>
After another ship, the Valor, crashes into the Ishimura, Hammond and Isaac retrieve the former's power core to repair the ship, but Hammond is killed by a Necromorph en route. Isaac is urged by another survivor aboard the ship, Dr. Kyne, to return the Marker to its former spot on Aegis VII, but he is stopped by Kendra who reveals herself to be an undercover government agent with an agenda. She kills Kyne, and Isaac, with Nicole's help, is able to stop her from taking the Marker. He restores the artifact to Aegis VII, but this disrupts the planet's gravity tethers and Isaac must escape before it implodes. However, before he can leave Kendra reappears with a video file showing Nicole committing suicide before Isaac's crew arrived at the Ishimura. Isaac's interactions with Nicole were merely hallucinations induced by the Marker.
br>
After one final battle with the Marker's Hive Mind, Isaac escapes the planet. But, while in his shuttle flying away, he is attacked by a disturbing vision of Nicole.