Since Dean had his Vkandis ritual to do at dawn, and Sam owed him for being late to the house on Sunday, he'd stayed with Grace on his own until Dad and Zoe had come home from their vacation. By the time he heard all about their trip - the good details, not the gross ones - and got them caught up on how Grace had been over the last few days, it was late in the morning, and Sam was thinking about stopping and getting donuts for himself and Peter as he headed back through town and checked his voicemail.
He hadn't gotten far when the most recent message
stopped him in his tracks, and he listened to it two more times to make sure that he was hearing everything correctly. Your father is an acquaintance of mine.
Sam knew what that meant - the guy had to be a hunter, and if he'd gotten the one-up on Dean, he had to be a good one. Dean's fine for now
started up the knot in his stomach, and it was all Sam could do to keep from panicking, to keep breathing and try to figure out what to do.
If this Walker guy was serious, Sam couldn't risk going back to talk to Dad and Zoe, not if Dean's safety was on the line, and going back to his room to get Peter would have been just as risky. It was possible that the whole thing was a lie, that Dean wasn't even there, but Sam had expected him to come back to the house after his ritual. He hadn't thought much of it when Dean hadn't, but now it was just one more sign that his brother might be in serious trouble.
Sam still had enough sense to go to the weapons locker and grab some of the smaller knives he kept in there, but as he headed for the woods, all of his thoughts turned to Dean. He couldn't form a full plan without knowing exactly what this was all about, but that didn't stop him from trying to come up with a few ideas to make sure Dean stayed safe. Dean's fine for now
wasn't good enough, not at all, and Sam didn't slow down until he got close to the spot Gordon had mentioned in his message. [For those who know who they are, dun dun dun!]