Sam: You built a panic room??
Bobby: I had a weekend off.Dean: Bobby, you're awesome.
On the big metal door to Bobby's panic room, we stamped in the name of Eric (Kripke's) grandfather's steel company...It's a nice thing for Eric.
The panic room, which is located off the basement in Bobby Singer's house, was built and designed by Bobby Singer during a weekend off from hunting. The room is designed to offer safe haven from ghosts, demons, and angels. It can also be locked from the outside and used to imprison people. Sam has been its most frequent, and also reluctant, occupant.
It is a cylindrical room, completely lined in iron coated in salt to keep spirits from entering. In the roof is a large extraction fan, below which has a grill with metal work in the shape of a devil's trap. There is also a devil's trap that spans the entire ground inside the panic room, a devil's trap painted on the ground outside the door, and Enochian sigils on the walls that keep angels from entering.
The room has a cot and a bed that folds up against the wall, two desks, two chairs, a mirror, and a bookshelf. It appears to be well-stocked with supplies and equipment, such as a transistor radio. Many of these items are removed when Sam is imprisoned in the panic room to detox from demon blood. There is an iconic poster of Bo Derek from the movie "10" on the wall, which Dean and Sam raise their eyebrows at when the first see it.
While being attacked by the Witnesses, Bobby leads Sam and Dean to a safe room in his house. Here they do the research that reveals that someone is raising the Witnesses as part of starting the Apocalypse.
Locked in the panic room to withdraw from the effects of the demon blood, Sam hallucinates and then starts having convulsions and being flung around telekinetically. Dean and Bobby handcuff him to the bed. Later Castiel arrives and, unbeknownst to Sam, uses his powers to undo the bonds and open the door to the room. When Sam has gone Castiel locks the door from the outside.
Dean is locked in the panic room as Sam fears he will leave to say "yes" to Michael. When Castiel comes to check on Dean, he uses an angel banishing sigil to send Cas away and escape. Later, Sam again puts Dean in here, this time handcuffed to the cot, but he chooses to release him, and take him to rescue Adam.
Bobby traps Sam in his basement, but Sam manages to sneak out by unscrewing the devil's trap-covered ceiling vent in the panic room. Later, Bobby and Dean lock Sam in the panic room, chained to the cot, after he tries to kill Bobby. At the end of the episode, they watch at the door while Death returns Sam's soul.
After Castiel removes the barrier in Sam's mind that keeps him from remembering his time in Hell, Sam is unconscious. Dean and Bobby lay him on a cot in the panic room to make sure he's safe while they go to confront Crowley and Castiel. In light of Castiel's actions, angel proofing was added to the walls of the panic room, and Balthazar confirms that the symbols are accurate and keep him from entering.
- Singer Salvage Yard for more information on Bobby's house.