This, to get a human level 5 fighter/rogue. Who could be a poly morphed spy.
Well...there are a lot of ways this is correct:
* She would need to be of some significance to bother entering enemy territory at all for. A general, a commander, powerful by her own ability, connected to someone powerful, knowledgeable about someone powerful...
* They would not need to actually go to her to get any and all information she has. Teleport is a 5th level spell. So is Sending. And Dream. and Nightmare.
While Teleport is the most common of those spells for an arcane caster, likely to be taken by any that can get it, Sending is also a well known and well used. Added to that, Sending is on the Cleric spell list as well. As a 4th level spell.
Basically, instead of even thinking about having someone cast a Teleport, the smart thing would be to load everyone up with Sending one morning and have them cast it at her all day long. She can even talk normally; they'll have spells to spare.
Run out of Sendings? Do it again tomorrow. And the day after that.
* Now, someone said finding out whether she is a spy is easy...and it could be, if you have the right spells/items/people. How will you check though? Teleport to her?
Getting directions for the Teleport would take a Sending in and of itself, then you have to worry about an epic lich and a city of Goblins one shotting you. Not worth it.