How do you get the quest Still in the dark in Fallout New Vegas?

To start the "Still in the Dark" quest in Fallout: New Vegas, you need to first complete the "The House Always Wins" quest line and reach the point where you have access to the Lucky 38 casino. Once there, speak with the character named "Yes Man" after you have the option to access the Securitron army. This will trigger the quest, leading you to investigate the hidden secrets of the Brotherhood of Steel.