Sherry Birkin is the daughter of William and Annette, two of the most brilliant umbrella scientists. She wore a pendant since birth, that secretly held a sample of the G-Virus. Sherry didn't know about the city becoming infected with zombies, until her mother called her to tell her that it was not safe to stay at home, and that she should come to the Raccoon City Police Station.
Sometime after that while Sherry was walking around, she actually heard to people talking, she was happy to actually hear another person's voice, since the last one she heard was someone screaming. When she heard that someone was walking her way, thinking it was another one of the zombies she hid, then she was easily found by Claire Redfield, another person who was looking for a way to escape this tragedy. Sherry didn't realize at first that it was actually someone who wasn't one of them, but when she did she hugged Claire, and began to cry. After the two begin to know each other a bit, Sherry warns Claire about the monster that is coming after her, then when the two hear the strange noise, Sherry quickly runs away, so Claire wouldn't get hurt by the monster.
Later Claire runs into the Sherry again, and the two both go into the sewers on their search to escape the infected city. While the two had been inside of the sewers, they got separated. Exploring through the sewers, she managed escape from a Zombie and cockroaches through shafts. When she did get a hold of a Wolf Medal the ground fell beneath her, the bags of garbage that were below her thankfully did break her fall, but was sadly knocked out by the impact. While she had been unconicous and helpless, Sherry was implanted with the G-embryo by her father.
When Claire managed to find Sherry, she went to go find a cure for her. While in the laboratory, Claire runs into Annette, before William had been able to arrive and fatally wound her. Before dying, Annette gives Claire the instructions for creating the G-Virus antidote. Soon after Claire created the antidote, she then attempts to make her escape, having Leon take Sherry to an escape train before the lab self destructs.
Their escape was backfired once again by Birkin, forcing them to fight the monster and incapacitate it. Claire then rushed to the train, joining Leon, and successfully administering the vaccine to Sherry. Unfortunately, Birkin, now a really huge monster attacks the train, which had triggered another self-destruct sequence. Claire, Leon, and Sherry escape moments before the train explodes, destroying Birkin once and for all.
When the three mangaged to finally escape, Claire left Sherry in Leon's care, when she went to go off to find her brother Chris. Then after she left, the two were found by the Government. Her safety was used to blackmail Leon into working for the government.