The Plot of Aliens: Dead Orbit in chronological order:
First contact
In 2295, an unknown vessel approached the Sphacteria, a fueling depot orbiting the gas giant Pylos. Park identifies the unmarked ship as an old Wey-Yu freighter that had been sold at auction to a private buyer, She also informed Captain Hassan that the ship contained Hypersleep chambers, and that the crew of presumed salvagers may still be in stasis. Communications Officer Rook is less than enthusiastic about the whole event, believing they may be pirates. Captain Hassan tells Wascylewski and Park they are all going to shuttle to and board the unmarked vessel, alongside Medical Officer Harrow and Security Officer Torrenson, leaving Rook behind.
Once aboard, the five crew-members explore its dilapidated interior, with Hassan calling it a "deathtrap". Wassy notices a massive hole through a wall, citing that something had melted through the bulkhead. As he catches up with the rest, the crew encounter three humans in hypersleep chambers: two male twins and a female. Wassy checks a terminal and observes that their vital signs seem normal. Hassan suggests waking them up, though Torrenson advises against it.
When Park flips the switch to open their pods something goes awry. The coolant tank breaks and the chambers begin violently overheating, burning the members in stasis alive. The group panics and eventually manage to bludgeon the chambers open, bringing out the horribly charred and disfigured passengers, choking and gurgling and in a state of shock before transporting them back to the Sphacteria.
Wassy grabs a bottle of alcohol along with a carton of cigarettes, attempts to leave for his quarters, but Hassan stops him and orders him to begin deciphering the ship's systems. Wassy subsequently recovers data that reveals that the ship's last entry had them exchanging supplies for Chinese Yuan, with only frontier colonies in desolate space (to which Rook heard rumors of a "cholera outbreak") still using the currency. Wassy deduces to to the others that if the crew initiated emergency procedures aboard the ship, then the vessel would have autopiloted them to the nearest corporate location, in this case, the Sphacteria. Additionally, he identifies that the ship originally contained eight crew-members, not three.
Double trouble
Park suddenly contacts Hassan, telling him that she and Harrow need immediate help. As Hassan and the others return to the med bay, they are met with Park and Harrow attempting to hold down the seizing twins, who had already been given a full dosage of sedatives. Suddenly, two Chestbursters erupt from them, and the others watch in horror as the creatures escape from the med bay and into the depths of the station.
Following Rook's disappearance, Hassan is snatched into a vent in front of the remaining groups very eyes. Park, Torrenson and Wassy all start weighing up their odds of survival. A panicked Torrenson wants to take a shuttle and retreat into the scavenger's vessel until rescue arrives whilst Park is concerned about Rook and Hassan still being alive.
After a heated argument, the group decide to check up on Harrow, still in the med-bay surveying the last remaining passenger. The three hear a crash and rush to the med-bay where they are greeted with the fully awake female salvager holding Harrow hostage with a scalpel by his neck. Park attempts to calm her down whilst Torrenson suddenly lunges at her with a stun baton. She is able to dodge him, however, and Torrenson stumbles into one of the operating tables, revealing one of the twins' corpses to the female. In a state of shock and rage, she brutally slits Harrow's throat and runs away. After Harrow bleeds out in Park's arms, the rest attempt to catch the female passenger. The group are too late, and they watch on as she takes the shuttle and leaves the station. The shuttle's umbilical however, is still attached, causing it to be propelled back into the Sphacteria, violently crashing into it.
In the aftermath of the shuttle colliding with the Sphacteria, Wassy, Torrenson and Park rush to the cargo hold, in which Wassy retrieves a case. The case is revealed to contain mining charges, the crew's last hope for survival. Wassy intends to lock everyone in life support and "blow the struts from the main deck"; since the station itself is modular, they'll be able to use the module as a psuedo-lifeboat and wait for rescue. Park suddenly hears a noise within the darkness of the cargo bay, and a Xenomorph suddenly emerges and attacks the group. Torrenson, traumatized, runs from the scene. Wassy and Park retreat to the observation deck in hopes of solace, and Wassy begins closing the bulkhead, telling Park to hurry. Suddenly, a second Xenomorph emerges. Wassy looks on in horror and despair as the two Aliens incapacitate and kill Park as the bulkhead is sealed.
04:03:36
Within the depths of the crumbling fuel depot known as the Scphacteria, the disheveled Engineering Officer Wascylewski is sitting in the quarters of the observation deck alone. Before putting out his last of many cigarettes, he notices a terminal warning him that a threshold has been reached and requires immediate attention. Wassy puts on a compression suit, brings a case with him and takes a space walk across the station.
Once safely back inside, Wassy removes his space suit after his walk and anxiously scours the corridors of the Sphacteria. As he turns a corner, he hallucinates a Xenomorph, only for it to turn out to be a mesh of pipes and machinery. As he recovers from his scare, a loose cord blasts steam into his direction, covering his field of view. As Wascylewski looks into the smoke-covered corridor, a real Xenomorph emerges from the mist. Wassy drops the case and runs into the medbay to hide, sitting down next to the corpse of one of the burned salvagers.
Wassy realizes that he forgot the case after his encounter with the Alien and goes back to retrieve it, securing it to himself with medical tape. A sudden hull breach results in him having to perform an emergency override and seal the bulkhead, but not before losing enough air to pass out. As he reawakens, he sees two Aliens by his side, one dragging him by foot down a corridor, before losing consciousness again.
02:02:58
When Wassy comes to, he finds himself cocooned in a nest next to an unconscious Hassan while the two Aliens watch over the both of them. Laughter in the distance suddenly lures both creatures away, allowing Wassy to break free and escape the nest with the case he originally set out for. He looks back at Harrow, still unconscious and cocooned, and reluctantly leaves him. Wassy follows the sound of the laughter until he finds a delirious Torrenson, right before the two Aliens he purposely lured out emerge from the darkness behind him.
00:59:59
Wassy runs away from the two Xenomorphs as Torrenson is killed. He reaches life support, puts on a compression suit from a locker and prepares the mining charges. Ready to take leave, he notices a bag containing a spare box of cigarettes in the locker. Wascylewski gives into weakness and takes them with him, before an Alien bursts from a ventilation shaft above him and attacks him. In a fit of confusion, Wassy pulls at the bag which accidentally brings the whole locker down onto the Xenomorph. This buys him enough time to detonate a charger and blow a wall into the ship, bringing him into the atmosphere of space. Wassy's compression suit allows him to stick to the surface of the station, but the pursuing Alien emerges. As the creature closes in, Wassy detonates another charge, separating the life support module from the station. As Wassy hooks himself onto the module to stop himself slipping away into space, the Alien emerges yet again from the smoke, this time missing an arm with acid blood dripping everywhere.
Wassy realizes this and unlocks a chamber containing several oxygen tanks. Wassy holds one up in front of the approaching creature and it's acid blood, floating through space, collides with the tank, blowing Wassy away and the Alien into opposit directions.
Adrift
After safely making it back inside what's left of the module, now drifting aimlessly in desolate space, Wassy breathes a sigh of relief and takes out his last pack of Pachyderm cigarettes. A terminal nearby suddenly warns that oxygen levels are critical and will only last 04:02:56. Wassy, alone, smokes his last pack as the timer slowly counts down.