If the doors did indeed all look the same, that simplified things quite a bit.

"I use a layered tracking spell that transmits sensory data back to me from a series of orb drones. It can lock onto signatures, and that's what we usually use it for, but it can also be used to look into areas that are too dangerous to enter personally. Now that I know what to look for, it shouldn't be too hard to find - unless it's shielded or guarded somehow."

He wouldn't go into the legalities of the spell just now; it had been used for criminal purposes before, and using it for such was considered a minor felony back home. It also wasn't his specialty; he could use it, but it was nowhere near as strong or precise as Nanoha's version. "The drawbacks are that it has a limited range and I'll be next to defenseless while I'm operating it." That was a problem Nanoha did not have; her Intelligent Device could operate the spell on its own, without input from her.