Help Please? Dong Huo's Keystone

[LlamaMama]

My sim has explored the Market Caves on her own, without having the quest for it, and has completed the tomb. Now she's exploring the other side, but does not have Dong Huo's Keystone. I've sent her back to Market Caves and reopened all the chests, but she has indeed emptied them.

Does she have to wait for this quest in order to get the keystone? Is it too late now?

Edit: To answer my own question, it's necessary to actually get the line of quests before the keystone will appear in the chest. There is no harm done by exploring the cave in advance.

[Pam]

Alrighty then!  Questioned answered!