Quoting: Albijoe
... but a clue to WHAT?
That you need to talk to someone in Namok to begin the next Plot element.
Since you say you've done that, you probably talked to the right person and didn't recognize the sign. Or maybe you hit a time limit on the overall story (the comment said 3 days or until you finish).
I looked into the other plot files in more detail and noticed one other possibility. Most of the plots involve a reaction check. Fail it, and the key person will blow you off and you will be unable to continue the story.
Possible blow-off texts:
Archeology plot:
* If the ruins I discovered were an ancient military base, I could get a corporate research grant for sure...
* If I'm really lucky I can write a paper on the ruins that we found.
* So many rusted broken things to catalogue...
Basement plot: (which is the one that gives the photo, but might recur...)
* I've got a huge secret, if only I had someone to share it with...
* My basement may be the key to everything...
* You'd think that all the good stuff around here had already been discovered. I'm hoping that it hasn't been...
Historic Site plot:
* Kids these days don't care about the past...
* Nobody in town wants to get involved...
* It's a shame what's become of the old park...
Stolen Plot:
* There's been a break-in at the museum, but rest assured that the guardians are doing everything we can to catch the thieves.
* I'm investigating some thieves who broke into the museum. You wouldn't happen to know anything about that, would you?
Tomb Plot:
* If only I were as handy with a rocket launcher as I am with a pocket calculator...
* Why is it that all of my grad students are weasely little guys? What I need right now is a real man...
* I'll be starting work shortly.
There are also three other possible plots -- one where someone sells you a treasure map and the two possible conclusions. None of those have reaction checks.