After some quick diagnostics, the Overseer learned that all her systems were functioning within normal parameters. She would have to run full diagnostics later, of course, but for now she needed to figure out where she is and what happened to her. All she could remember is that she was at her desk, watching the server room on her terminal when, suddenly, everything went dark.
She doesn't think she fainted, we can rule that out, synths don't faint. Right? Anyways, as she turned to her right, she noticed a square Brotherhood of Steel flag hanged on the wet wall.
"Damn it," she thought to herself, "it's those technology freaks again! They must have knocked me out with an EMP." It's the only logical explanation she could come up with at this point.
"Alright then, I'll just set myself free of these handcuffs and be on my way." The Overseer easily breaks out of her restraints and heads for the cell door. But the moment she touches it, a high-voltage current runs through her entire body and she falls to the ground, unconscious. Three minutes later, the system reboots and she's fully awake.
"Okay... So I guess I'll just stay here for a while."
A few hours later, a young soldier, a Brotherhood initiate judging by his apparel, approaches the cell.
"You're a pretty one, aren't you? I didn't know they made synths so hot. Damn, girl! I could almost fall for you, if I wouldn't know what a treacherous good-for-nothing toaster you are. Now show me them shooters!"
"Come closer," the Overseer whispers. As the young man approaches the cell door, the synth quickly reaches out, grabs him by the neck and smashes the poor bastard onto the cell bars, rendering him unconscious. Who are we kidding, he's probably dead.
"Men are so stupid," the Overseer thinks to herself as she grabs some keys from the man's right pocket. Unlocking the door, the synth tries to find a way out of her new found prison.
She manages to avoid all security, all the way to the main exit. The console that opens the main door seems... unhackable. This has never happened to the Overseer before, and now she's just staring at it for a good several minutes, trying to figure out her next move. She notices the radio transmitter on the wall. Luckily, that's hackable, so the synth sends out he following message:
"This is the Overseer of Vault 121. If anyone reads this, please notify my people that I need assistance at the following coordinates: latitude 50.00820, longitude -112.61440. Broadcast this message on my behalf on the 30 Hz frequency. My people should be able to pick it up. If you manage to successfully deliver this message to my Vault you will be rewarded with food, weapons, and as much purified water as you can carry. If anyone reads this, please send help."
The synth repeats the message five more times and then heads back into the belly of the beast, so to speak. But not before taking out a dozen of Brotherhood soldiers, just for the fun of it. Finally, someone manages to knock her out with an EMP grenade.