Instead, when the encounter happened, the players fluffed it. They made a heck of a lot of noise outside the room in which the NPC party (or rather, it's remnants) had made camp. The result being that they were ambushed with a sleep spell the moment they actually managed to open the door. Not unnaturally, their characters awoke bound and stripped in a dark room where they were interrogated by a understandably very jumpy NPC Magic User and his two surviving hirelings. All they had to do to prove they weren't doppelgangers or crazed dungeon residents to this NPC was answer a simple question: "Who sent you?"
Despite the fact that this NPC's name has come up in every single one of the previous nine sessions, not one of the players could remember the name. Not one. So the NPC killed one of them (randomly selected by dice roll) to jog their memory. And as it happened, the PC in question was the one character whose loss they could least afford.
Now, if we weren't specifically played an Old School game, and I hadn't specifically set out in advance that I would be unleashing a ruthless DM style on my players before hand, I would naturally have allowed the players to make an Intelligence check to see if their character could remember. Especially given that most of the players have been playing less than a year.
But I didn't. I didn't allow them the int check because:
- We're now ten sessions into the campaign and the name they were asked to remember has come up every session.
- I've been repeatedly banging on about how it's not my job to remember things on their behalf.
- The last time they forgot the name of an important NPC (just last session) I specifically warned my players that they needed to either start keeping better notes or else play closer attention to the actual play notes I post after each session.