How does Delphine know where the Horn is? [closed]

Solution 1:

All questions answered.

How did she know?
She's the acting Grandmaster of the Blades. If a half-naked drug addict can be Grand Spymaster during better times, she can probably figure a few things out.

It's also possible that everyone in Tamriel knew and the Greybeards were the last to know because the only person who ever goes near there is Klimmek. I mean, even bandits and necromancers were trying to raid the place.

Why Ustengrav?
Well, it is where Jurgen Windcaller's tomb is. Seems like a logical location.

How did she get in and out without killing anyone?
Well, of course she killed everyone. But then ten days elapsed and they were all okay. And the traps reset. It wasn't hard because she's essential.