Lenny:
Our characters shouldn't suffer for our daftness.
Hah, this edition is all about your characters suffering because you did something dumb. :p That said, I'm not the type to undult punish you for someone dropping from the game. You don't have the spear right now, but I'll be up front and say you'll be able to get it back.
Lenny:
DM, was there any signs of traffic in the necromancer's secret room? If there has been no movement in there for ages, there would be dust on the floor. Was there dust coating the interior of the wall-door?
There was a lot of dust but no sign of recent foot traffic.
Lenny:
Does the wall-door lock from the inside or only on the outside?
You didn't see a keyhole inside, but you didn't take a long enough look to know anything beyond that.