"Now that we've lost communications, there's nothing else we can do. Alright, everyone, we've gotta hurry up and find a way into that tunnel. It's gonna be our way out of here."
— Marvin briefs the surviving officers on their final escape plan.
When the t-Virus contaminated Raccoon City's drinking water and transformed thousands into Zombies within hours, Lieutenant Branagh was carrying out day-to-day operations within the Raccoon City Police Station. With Chief Brian Irons nowhere to be found; Deputy Chief Raymond Douglas killed on September 24, and the bulk of the police force wiped out in the streets on the 26th, Branagh was effectively in charge of what remained of the RPD. The police quickly lost control of the station as wave after wave of the infected continued to assault them, and suffered a number of casualties on the night of September 27. Finally, Branagh decided the only solution was to abandon the station entirely, and he and survivors Fred; Aaron; Tony; Rita, and several surviving citizens, began searching for an escape route, finally finding access to tunnels beneath the station. Though Rita was able to escape, having located fellow officer Harry outside of the station, Fred, Aaron and Tony were killed and Branagh seriously wounded/infected by Zombies, forcing him to remain behind. When former S.T.A.R.S. officer Jill Valentine explored the police station later that day, she discovered Branagh passed out and believed him to be fatally wounded. Really, however, he had been infected with the t-Virus and was in the process of mutating to survive the horrendous wounds he had; his injury therefore was no longer fatal.
By September 29, several police officers were left in the building, such as Elliot Edward, but it is unknown if they were still taking Branagh's orders. That night, Branagh met rookie cop Leon S. Kennedy, who was recently arrived on the job in Raccoon City unaware the rioting was more serious than reported. Branagh warned him that the station was not safe and that he should not hesitate to shoot his infected colleagues. He later transformed into a Zombie himself and was killed by either Leon or civilian Claire Redfield.