On the night of July 24, 1998, Alpha team was sent to the Arklay Mountains north-west of Raccoon City, in search of the S.T.A.R.S. Bravo team, who mysteriously disappeared. They soon discovered that most of Bravo was slaughtered by the monsters that were created by the Umbrella Corporation's t-Virus, and Alpha team were forced to spend the night trying to survive in the zombie- infested Spencer Mansion until the remaining members, along with the sole survivor of Bravo team; Rebecca Chambers, were rescued by helicopter pilot Brad Vickers. Joseph Frost was the only Alpha Team casualty during the Mansion Incident, although as of 2009, both Albert Wesker and Brad Vickers have also lost their lives.
Following their ordeal in the mansion, the surviving S.T.A.R.S members tried to tell the world what kind of experiments that Umbrella was performing, and the kind of monsters that were created. However, with all the evidence destroyed along with Spencer mansion, Umbrella used its influence to make corrupt police chief Brian Irons disband S.T.A.R.S. and make it's members lose all credibility. In one swift move, Umbrella was able to sweep the mansion incident under the carpet. Brad Vickers was killed by the Nemesis during the Raccoon City incident, just two months after the Mansion Incident.