Brett was the engineering technician, who served aboard the commercial towing vessel Nostromo and a good friend of his engineering chief, Parker.
While returning from a job in the Solomons, the ship passed through the Zeta II Reticuli system when the Nostromos onboard computer, "mother", awakened them from cryosleep prematurely. During breakfast, Brett and Parker complained about the "bonus situation", stating that they were unsatisfied with the share percentage they were receiving for their work. When the ship's captain, Dallas, ordered the crew to respond to a distress beacon, Brett and Parker angled for full shares. They reminded Warrant Officer Ellen Ripley, that rescue work was outside their job description.
The Nostromo crew responded to the beacon and took a drop ship to a planetoid, which later came to be known as Acheron. The weather conditions on the planetoid's surface were extremely violent and the ship suffered extensive damage while trying to land. Brett and Parker noted that it would take anywhere between seventeen to twenty-five hours to affect repairs.
While Brett worked on repairing the damaged drop-ship, three of the other crew members explored the planet's surface and first officer Commander Kane was injured by an alien embryo. Despite quarantine procedures, both Kane and the embryo were brought on board and Kane later died from his injuries. The embryo escaped quickly grew into a seven-foot, adult-sized Xenomorph and began hiding in the air ducts of the ship. The rest of the crew had yet to realize how large it had grown.
Captain Dallas charged Ripley, Parker and Brett with the task of hunting the creature down. While Parker brought along a net, Brett carried a cattle-prod with him. Ripley used a tracking scanner designed by their science officer Ash to get a lock on the alien's location. While exploring the cargo bay, the scanner locked in on a signal, but it only turned out to be Ripley's cat, Jonesy. The cat ran off and Parker and Ripley sent Brett out to recover it. They needed to catch the cat or else it would just continue to send out false signals. Brett found Jonesy in the maintenance bay, but unfortunately for him, he also found something else. The Xenomorph descended from the upper workings of the bay and speared Brett with its secondary jaw. It then wrapped its tail around him and dragged him up into the cooling ducts.
- An alternate death for Brett takes where instead of being killed by the Xenomorph it drags him into the ducts alive. It is later revealed that he's "alive" when Ripley is making her escape from the Nostromo and discovers the creature's lair. Ripley finds a cocooned Brett and Captain Dallas being transformed into eggs to produce more creatures. Brett is killed by Ripley by the urging of Dallas to kill them, she hesitantly obliges by incinerating her crew mates with a flamethrower.