Plot
Dead Space: Downfall takes place in the year 2508, centuries after humanity narrowly avoided extinction due to resource depletion by "cracking" planets to extract their resources in a three-year process. The story begins during the second year of an illegal mining operation on the planet Aegis VII funded by the Church of Unitology. Colony geologist Jennifer Barrows discovers a monolith-like artifact identified as a Marker, an object sacred to the Unitologists' beliefs. In reality, the Marker is a human copy of an alien object that begins to have a fatal influence over the colony, eventually causing an outbreak of reanimated mutated corpses referred to outside the movie as "Necromorphs". Downfall details how the Marker's infection reached and overcame the Ishimura, told through the eyes of a number of Aegis VII miners and Ishimura crew members.
The film opens in media res with a video message from security chief Alissa Vincent, saying the Ishimura is lost and both the ship and the Marker that caused its fall must be destroyed. The story goes back to Barrows' discovery of the Marker in an area showing signs of ancient human mining. By the time the Ishimura arrives, the Aegis VII colony has undergone a catastrophic breakdown, with dozens killed and many reports of violent behavior and psychosis. The Marker is brought on board on the authority of Captain Mathius and Dr. Kyne, prompting many Unitologist crew to worship it, among them engineer Samuel Irons. Vincent grows increasingly furious about having the Marker on board, believing it was responsible for the colony's collapse.
After planetcrack, all contact is lost with the colony, which is completely overrun by Necromorphs. The now-insane Barrows kills herself, and when her husband escapes with her body to the Ishimura, they are infected by a stowaway Necromorph and escape onto the Ishimura. Kyne, already questioning their real mission to bring the Marker back to the Church, briefly sees the converted Barrows. Vincent's six-person team—including members Ramirez and Hanson—investigate a disturbance, finding growing numbers of Necromorphs killing the crew and overtaking the ship. During their encounters, her team loses two members, and Hanson is only saved by Irons's intervention. Meanwhile Mathius grows increasingly paranoid and delusional, forcing the bridge crew to restrain him. Kyne's attempt to sedate him leads to Mathius's death, and Kyne flees as all escape pods are launched, trapping everyone on board.
En route to the bridge, Hanson goes insane and kills Shen, another member of Vincent's crew, before Ramirez shoots him. In an effort to save survivors, Irons sacrifices himself to hold off the Necromorphs. Vincent and Ramirez then go to stop Kyne deactivating the Ishimura's engines and crashing them into Aegis VII. Ramirez dies during the trek, and Kyne reveals the Marker's influence to Vincent before escaping again. With the Ishimura stable but in a decaying orbit, Vincent reaches the Marker, which the Necromorphs cannot approach as it kept them sealed on Aegis VII. Exhausted and beginning to suffer from hallucinations, Vincent makes her video message, then attempts to escape on a remaining shuttle. Trapped by Necromorphs, she opens the bay doors, sending herself and nearby Necromorphs into space after launching a distress beacon. The film ends with the UGS Kellion responding to the distress call.
