She goes around the club, like she said, keeping an ear out for vampires.

Also her eyes. In case any pop out in her peripheral vision or something.

Nnnnope.

"… So there is either some vampire party going on, we have some rare demon that eats them all, or what, they all coincidentally just decided it was a bad night to go out?"

"A meeting of vampires... is not out of the question."

"I don't suppose there's some low-magic spell we can use to find a large congregation of vampires…?"

"The closest thing to that is your senses."

"Should I try it now, then? Shut my eyes, stand still, and…?"

"It would be easier with a vampire here so you could focus on them, but you should be able to—sense them."

She nods and tries it!

She's a little bit hyped, a bit on adrenaline because she expected to find a vampire, so she's probably not in the best state for sensing things right now…

Yeah there's no sensing going on, there.

… She tries it a bit longer?

Nnnnn—maybe?

She keeps at it for a bit longer.

Yeah no that was totally a fluke.

So she opens her eyes and hopes her friends (and mentor?) haven't been quietly eaten!

Nope, they're all whole and uneaten.

"Did it work?"

"Unfortunately not," responds Eva. "Thought it might have for a moment, but nope."

"Okay, so... any ideas about, like, why there are no vampires anywhere?"

"I think it's pretty much 'vampire party', 'vampirovore', 'freak chance'?"

"Vampire party's kinda broad..."

"And I would normally say a vampirovore is less likely than chance but this is Sunnydale."

"I mean, I got the impression vampires didn't team up overmuch so vampire party is probably low-chance, other than, like, if there were some person dropping lots of blood around somehow." Pause. "So, horrible idea and all, but do vampires do – like, keg parties, except with humans?"

"They don't do keg parties, but sometimes they do get together to plan apocalypses."

"… Why?"

"Because they're evil demons and that's what they do," she shrugs. "Most vampires don't aspire to such lofty goals, but some do, and they do tend to draw likeminded—or just bored—individuals to their cause."