Vera Keyes was a well-known starlet before the war and one of the celebrities invited to the Grand Opening of the Sierra Madre Casino. She had a special connection to the casino - she was the inspiration for its construction by its founder, Frederick Sinclair. Sinclair worshiped the ground she walked on, and built the casino as both a monument to her and a fortress to protect her.
Vera’s voice was the key to the casino’s vault, specifically, the words “begin again” and “let go”, spoken in her voice into a specific terminal in the casino would activate the elevator down into the casino’s bowels.
On the night the bombs dropped, the night of the Grand Opening, the casino locked its doors and its security systems activated. The holograms massacred the guests, and Vera was trapped in her room, with only one way out. She wrote her last words on the wall, and took an overdose of the chem cocktail which had both saved her from and caused so much pain already.
A malfunction with the Emergency Broadcast, something to do with the Gala Event drawing power from the security systems to save money, caused the advertisement for the casino’s grand opening to be sent across the airwaves, rather than the intended broadcast. For over two centuries, Vera’s voice would act as bait, not for the rescue Sinclair had hoped for, but for potential treasure hunters, luring them to their deaths, urging them to come to the Sierra Madre - a place where they could begin again.