“We were part of a caravan heading into New Vegas from down south. They are holding us hostage, trying to get some ransom. Anyone willing to pay for us died in the attack. Once the Fiends figure that out, we are as good as dead.”— Rick Lancer
Three Caravaners, Rick Lancer, Rachael, and Dennis, are being held within Vault 3 by Fiends, within the holding cells in the living quarters. Speaking to Rick will inform the Courier that they were kidnapped and that there is no one left alive who would be willing to pay a ransom for their release. Therefore, it is just a matter of time before the Fiends realize this and kill them, so he asks for the Courier's help. He tells them that a Fiend named Daniel, who can be found in the sleeping area behind the holding cells, has the key.
Rick also mentions that Carter, a fourth member of the group who is now dead, knew the password to the overseer's computer. One can intimidate him to get the password immediately, or agree to get the password if they help them all escape.
One can pick the lock of the cell door (Hard), or find Daniel in a room towards the back of the sleeping area, and either kill or pickpocket him to get the key to the cell. Return to free the prisoners. After opening the cell doors, Rick will initiate dialogue and tell the Courier the password. The three Caravaners will sneak out of their cell and leave the Vault.
The reward is the password to the overseer's computer, which unlocks underwater rooms with gun cabinets in them, positive Karma and 100 XP.
The freed caravaners will not be attacked by the Fiends, even if discovered.
Killing them does not result in any loss of Karma. Strangely, even if all of the captives are dead, positive Karma is earned by unlocking the jail door.
Sometimes, the prisoners will spawn outside of the cages. They will still have dialogue as if they were imprisoned, and the Fiends will not seem to notice either. [verified]