- "Priority one
Insure return of organism for analysis.
All other considerations secondary.
- —MOTHER's order directives[src]
Special Order 937 was a classified retrieval order given by Weyland-Yutani to Science Officer Ash aboard the USCSS Nostromo. The order's main priority was to preserve the Xenomorph specimen that was encountered by the Nostromo in the Zeta II Reticuli system and bring it back alive for analysis. All other priorities are considered secondary and all of the Nostromo's crew members are deemed expendable.
In 2122, the Nostromo's onboard computer, "MOTHER" intercepted a distress beacon originating from the planetoid LV-426 within close proximity to the ship. The crew members are awakened prematurely from their hypersleep, the crew responded to the beacon and took the Nostromo to the planetoid. Executive Officer Kane was impregnated by a parasitic life form discovered within an ancient derelict space craft found on the planet's surface.
Kane was taken back to the Nostromo for medical treatment, only to die moments later when the creature that was impregnated within him grew and bursts violently out of his chest while being witnessed by the entire crew. The surviving crew members soon discovered the truth and discovered that Ash was a synthetic. The crew destroyed Ash and planned to escape, but the creature soon hunted down the remaining crew, leaving Warrant Officer Ellen Ripley and her cat Jonesy as the remaining survivors. Ripley managed to escape the Nostromo using the shuttlecraft Narcissus and succeeded in killing the creature.