Alissa is headstrong and protective of human life, often leading her into conflict with her superiors. During the incident aboard the Ishimura, she was responsible for saving a fair number of civilians as well as stopping Kyne from scuttling the ship, though the Ishimura would remain in a deteriorating orbit until the arrival of Isaac Clarke. Alissa would not survive the incident however, sacrificing herself in a futile attempt to launch a warning beacon.
Dead Space: Downfall
During the massacre on Aegis VII, Alissa demanded that the Ishimura send a squad down to investigate the situation, but was repeatedly denied by Captain Benjamin Matthius. After a shuttle that fled the colony crash lands into the docking bay of the ship, she leads a squad of Security Officers to investigate the wreckage. To their horror, they discover the shuttle covered and surrounded by pools of blood. They then proceed to follow a trail of bloody footsteps leading away from the wreckage.
The trail leads them to the Morgue, where they discover the mutated body of Hans Leggio, a homicidal and suicidal prisoner. The body suddenly springs back to life and mortally wounds Dobbs. He is eventually gunned down by Alissa and her team in a hail of bullets. Shen, another teammate, moves to comfort Dobbs, but out of the shadows comes another Slasher, a female nurse once in charge of keeping watch over the prisoner.
After killing the creature, Alissa eventually leads her remaining squad in a futile effort against the Necromorphs. Pendleton dies in a firefight between the Necromorphs; Alissa and the rest are saved by a man named Samuel Irons, a devout Unitologist. He rips the Necromorphs apart with a Plasma Saw, inspiring Alissa and her team to do the same.
Leading the remainder of her team back to the Bridge, they engage in another fight with the Necromorphs. One of her members, Hanson, eventually goes insane and kills Shen by splitting her in half length-ways with a Plasma Saw. Hanson attempts to kill Alissa as well, pinning her down and attempting to shove the Saw into her head. Alissa holds out long enough for Ramirez to kill Hanson.
Eventually, Alissa is successful in returning to the Bridge and discovers that Dr. Terrence Kyne has overridden the ships gravitational controls and is planning to crash the ship into the planet below.
Along the way to stop Kyne, the remaining members discover a group of survivors being attacked by Necromorphs. Not wanting them to be killed, Alissa offers to distract the Necromorphs while Irons and Ramirez rescue the survivors through the vents. Irons, however, forces Alissa to take his place as he decides to distract the Necromorphs instead. Alissa and Ramirez help the survivors through the vents to safety. Helping the last survivors escape to the Bridge, Alissa and Ramirez watch in horror as Irons is killed and turned into a Necromorph by an Infector.
Alissa and Ramirez eventually reach the door to where gravitional controls are but discover that Kyne has locked the door. Ramirez manages to override the lock while telling Alissa the irony of his decision to work for security rather than the military. Realizing he too is succumbing to the same madness that consumed Hanson, Ramirez sacrifices himself to slow the Necromorphs down in front of the locked door. Vincent listens to Ramirez's screams of pain behind the locked the door before proceeding onto the control room.
Alissa confronts Kyne who explains that the Red Marker is responsible for everything, and that it must not be returned to Earth. However, Alissa is not willing to sacrifice the lives of the surviving crew of the ship for the greater good. The two in get into a heated fight, with Alissa able to successfully subdue Kyne and restart the engines. However, Kyne flees, taking Alissa's weapon along with him before he can submit the codes needed to deactivate the drift.
Alissa wanders aimlessly to the docking bay and is confronted by a horde of Necromorphs. She makes for the Red Marker and hunkers in front of it. There, Alissa discovers that they are unable approach the Marker, blocked by some invisible force. Helpless, Alissa sleeps under the protection of the Marker. Waking a while later, she is greeted by an apparition of Ramirez. Ramirez urges her to finish the mission, but when she asks how, he disappears.
Alissa notices the downed shuttle in the bay immediately and realizes what she must do. She makes her way to a computer station and records a video log telling those who might see it that she believes that the Marker is responsible for everything; that it and the Ishimura must be destroyed. After recording the message Alissa activates the venting cycle and makes a mad dash for the shuttle.
As the doors open - subsequently blowing numerous Necromorphs into the vacuum of space. Alissa, while hanging onto the shuttle for dear life, manages to activate and launch a distress beacon from the shuttle into space.
Despite her valiant efforts to hold on, Alissa is blown into the vacuum of space. Her body drifts off into the darkness as the USG Kellion approaches Ishimura, responding to the distress signal sent by Alissa.