Sam had no idea how that door had opened. One second he had been trying to ignore another figment of his fucked up imagination, the next the panic room door was swinging open and hitting the wall behind it with a dull thud. That was the noise that had gotten Sam's attention. Just a tiny, little noise and everything had changed. Sam had jumped up in uncertainty from his cot, he had waited a long moment for either Dean or Bobby to come walking through the door with his next meal - but neither of them did. No one came walking out at all, which left Sam wanting to do nothing less than the obvious: make a break for it while he still had a chance. Surely there was someone out there - perhaps even someone looking to screw around with him - but he was more than ready and willing to try and make a run for it anyway. He'd take his chances against the odds out there, even if it seemed far more likely that this was all a really bad prank. Sam was desperate and crazy enough to try.
He quietly and carefully moved for the door. Taking a deep breath, Sam poked his head out the doorway, peered out into the dark area that surrounded the staircase ahead, and took a step out of the room. He waited for something to happen. Dean to jump out and shout a surprise, Bobby to nudge him back into the room....something. Neither of those things happened though; Sam was still standing alone in the dark by the time he counted to three, making him realize that the door had indeed opened without either of their consent. Unless they were really messing around with him, which Sam didn't think was as likely now that he was standing outside the door in a deep silence. It was late. They were probably fast asleep. Sam rubbed at his neck, gave the door one final look, then swept forward and up the staircase. He took each step carefully and quietly, not wanting to bring any attention to himself if he could help it. As soon as Sam hit the top of the stairs, he listened for any signs of activity on the ground floor.
Nothing.
Quickly, Sam slipped out into the hall and made his way for the salvage yard. On the way out, he snatched his jacket up from the table and shrugged it on. Fingers shakily running through his hair, Sam crept into the salvage yard as carefully as he could. He was going to need a car. Fortunately, Bobby had about half a dozen of them laying around. He couldn't take any of the scrap obviously, but if he knew the man as well as he thought he did something drivable would be around here somewhere...