Rebecca Chambers was a rookie member of the S.T.A.R.S. Bravo team, with experience in the field of biochemistry. She is the sole survivor of the S.T.A.R.S. Bravo team, and also one of the four former S.T.A.R.S. members still alive.
A gifted girl, Rebecca was able to graduate university by the age of 18. Her expertise in chemistry and medicine earned her a position in S.T.A.R.S. as Rear Security (RS) for Bravo team. She became the unit's youngest (and most inexperienced) member which made her quite nervous around her teammates. Because of this, she is eager to please and has been known to take on any task assigned to her without hesitation.
On July 23, 1998, Rebecca was sent to the Arklay Mountains on her first case to investigate a series of cannibalistic homicides. During Bravo team's search of the area, they discovered the wreckage of a military police van, along with the corpses of the drivers and guards and documents of a prisoner, Billy Coen, that was being transported to a Military base for Execution.
Upon further investigation of the area, Rebecca uncovered the Umbrella Corporation's secret company train, the Ecliptic Express. Rebecca, chose not to radio for backup as she believed she could handle things by herself. Within the train, Rebecca immediately encountered the passengers, who were already turned into zombies as a result of an earlier attack. Rebecca was able to fend for herself for a time and met with the fugitive, Billy Coen. After witnessing the death of Bravo team member Edward Dewey, as well as the appearance of mutated animals, Rebecca and Billy made a temporary alliance and teamed up.
The train began to move again, due to the dexterous manipulations of Umbrella operatives sent by Wesker and Birkin.
The train eventually arrived at Umbrella's top-secret training facility within the region. Rebecca and Billy assisted each other throughout, overcoming many of the facility's traps and obstacles, as well as many of the Bio-Organic Creatures that were being raised within the structure. These events were able to strengthen Rebecca's trust with Billy, to the point that she lied to her commanding officer Enrico Marini, when he asked for Billy's whereabouts via radio.
Eventually, the two found themselves at a tram car, which led to another of Umbrella's underground labs. Although briefly separated, the two eventually found each other and made their way to the deepest levels of the facility. They met with the true culprit behind the outbreak, James Marcus. Marcus was a founding member of Umbrella who was betrayed by his apprentices, but was revived after being consumed by his genetically-altered leeches that were infected with the Progenitor Virus. Marcus transformed into the Queen Leech. Although he seemed impervious to firearms, Rebecca and Billy quickly discovered that Marcus was vulnerable to sunlight. Billy baited Marcus while Rebecca was opening the roof hatch eventually exposing Marcus to the light of day and destroying him for good.
Rebecca and Billy parted ways, with Rebecca taking Billy's dog tags as a reminder of him and the events that took place. Rebecca rendezvoused with the remainder of her team within the Spencer estate.
Rebecca managed to find the bedroom and fell in to a deep sleep, waking up after having a nightmare. There she met up with Richard Aiken and the two searched the grounds for captain Enrico Marini. However, due to a heightened amount of Web Spinner's, the two stopped the search.
Alpha team was later sent to rescue Bravo team and Rebecca met with Alpha team member Chris Redfield. The two teamed up, with Rebecca providing her superior intellect in situations that required it, such as playing a piano or mixing chemicals, while Chris saved Rebecca's life on a few occasions.
Eventually, the two uncovered that Alpha team leader Albert Wesker was the one who masterminded the deaths of several S.T.A.R.S. members and was personally responsible for Enrico Marini's assassination. However, Chris and Rebecca eventually foiled Wesker's plot, with Chris and Jill destroying the experimental Tyrant whilst Rebecca activating the self-destruct mechanism of the lab that Wesker had installed. Rebecca, Chris, and Jill escaped on the S.T.A.R.S. Alpha team helicopter piloted by Brad Vickers. Barry Burton somehow managed to survive the Mansion incident and returned to Raccoon City.
Upon her return to civilization, Rebecca wrote a police report detailing Billy Coen's death. Rebecca's current whereabouts are unknown. Series producer has stated that a 2nd Resident evil movie may have Rebecca as the star so as to update fans on her doings.
In Resident Evil 5 under the Resident Evil series History file it lists Rebecca as one of the surviving members of the Arklay Mansion incident.