Millburn was hired by the Weyland Corp to partake in an expedition aboard the USCSS Prometheus to the distant moon LV-223. After spending two years in hypersleep, Millburn along with the other crew members were awaken. While the crew members were having breakfast, Millburn approached Fifield to offer his friendship to him, only to be coldly rejected by the latter. As the Prometheus nearly arrives on LV-223, Vickers, Shaw and Holloway briefed the crew on their mission to find the Engineers. Once the Prometheus lands on LV-223, the team (consisting of Shaw, Holloway, David, Ford, Jackson, Fifield and Millburn himself) explores a large artificial structure nearby. While inside the temple, the team came across a water-related terraforming system that made the air within the temple breathable. As the team made it deeper into the temple, David activates the temple's hologram, which led them to the corpse of an Engineer. Millburn later separated from the others and followed Fifield further into the temple. Due to a rapid windstorm, the team were forced to return to the Prometheus. Millburn and Fifield, however were unknowingly left behind and had no choice but to stay in the temple until the windstorm calms down.
While inside the temple and coming across dozens of Engineer remains, Fifield fills his suit's own respirator with marijuana, which Millburn finds amusing. The two soon encounter two Hammerpedes that emerged from the black liquid. Fascinated by the creature, Millburn recklessly tries to make contact with it, despite it displaying obvious sign of threatening posture, only to be attacked by the creature. It wraps round his arm, tightening and breaking it. Fifield used his axe to cut the Hammerpede's head off, resulting in his helmet being sprayed with acid, causing him to fall into the black liquid, which catalyzed the melting of his helmet. The Hammerpede regenerated its head and climbed into Milburn's suit. It then proceeded go down into Milburn's throat and kill him. His body was later discovered by the team that was sent to rescue him, with the Hammerpede emerging from his mouth.
- Millburn actor Rafe Spall also played both Holloway and David as part of Noomi Rapace's screen test for Prometheus.
- A common criticism directed at Proemtheus is the fact that Millburn, who is supposedly an expert biologist, immediately attempts to pet a potentially dangerous extraterrestrial creature upon encountering it, particularly given the aggressive posture of the Hammerpede in the film.