Aliens: Fireteam Elite/Rescue

Final Part
You will eventually reach a locked door, along with crates containing items and an ammo crate. You will need to interact with the door to get to the scientist, though once the door is being cut open automatically, Aliens will bergin to attack. This is also where the Xenomorph, dubbed Monica, will reappear. Monica will behave essentially like the Xeno drones, where she will hide if she is significantly damaged and reappear after a while. Make sure to eliminate the other xenos while the Monica xeno goes into the vents. Also be aware of any spitter xenos because they can be sometimes hidden behind some of the scenery. It is recommended to stay close to the target door so that the aliens do not flank you, though you should also try to stay out of the close combat range of most of the xeno types.